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Customer-Premise Switching

System Features

The main purpose of both TDM and IP customer-premise switching systems is

identical. They connect voice users in the office to one another and to external

users over a pool of shared trunks. The differences lie in the way the two types of

switch accomplish their objectives. Telephone functions have evolved over more

than a century and users are accustomed to how they work. Each new generation

of switches has brought features that its predecessor could not support, but it also

supported the older features as well. The result is a suite of features that most

customer-premise systems support regardless of technology.

If trunk pooling was the only purpose of CPE switches, they could be

quite simple devices, but PBXs, and to some degree key systems, have a more

important role of unifying the office. CPE switches do for voice what the LAN

does for data; they bind the office with shared applications. It is logical, therefore,

to consider unifying voice and data into a single system that supports both. To

some degree this is possible, but the requirements of voice and data are much

different and most users care little or nothing about how the mission is accomplished.

They do care about features, however. Users expect similar features

whether the platform is TDM or IP. As we will discuss in Chapter 26, the strength

of IP lies in its ability to provide features that TDM switches find difficult or

impossible.

The office switching system is a strategic investment for most companies.

A PBX ties your company with your customers, suppliers, the public, and

other parts of the organization. The features it has and the way it is set up

and administered have a significant effect on how those on the outside view

your company. This chapter discusses the principal features of CPE switching

systems.

KEY SYSTEM FEATURES

Most manufacturers offer separate key system and PBX product lines, although

the functions may be nearly identical, at least in larger line sizes. Most TDM manufacturers

also offer a cross between a PBX and a key system known as a hybrid.

Table 24-1 lists the principal differences between these three types of system, but

these distinctions are not absolute. The feature differences between product lines

are many and varied, and some applications such as voice mail are universally

available on all systems. This section discusses features that are common to key

systems, which can be defined as CPE switches having the central office lines terminated

on telephone set buttons. In such systems, users answer incoming calls

by pressing a line button. If the call is for someone else, it is announced over an

intercom. To place an outgoing call, the user selects an idle line by pressing a button.

The physical size of the telephone set eventually places upper size limits on a

key system. When the system terminates more than a dozen or so lines it is easier

for users to dial 9 to access a line than to cope with all the buttons on the phone.

Key systems and hybrids often use the same hardware and software platform.

The distinction between the two is a matter of how the system is set up.

Key Telephone System Features

At one time key systems were electromechanical devices that had a limited set of features. New electronic systems have far surpassed these limitations, but the features of the last generation of electromechanical key systems defined the way users expect key telephones to work. The principal features are designated with illuminated buttons. A dark button indicates an idle line and a solid light denotes that the line is in use. A slow flash indicates an incoming call and a fast flash shows that the line is on hold. These buttons and lamps define the following features, which are common to all key systems:

Call pickup: Any station can access a line by pressing a line button.

Call hold: A hold button (usually red) can be pressed to hold the line in the central unit. By contrast, the hold button on a POTS phone holds the line in the telephone so the line cannot be used for another call.

Intercom: Acommon path shared by all telephones is used to announce calls.

Supervisory signals: Lamps show when a line is ringing, in use, or on hold.

Common bell: A bell common to all lines signals an incoming call. A slow lamp flash shows which line is ringing.

The central control unit is known as a key system unit or KSU. Electronic KSUs can support many additional features that are characteristic of most key systems. The list below is in addition to the telephone set features such as last number redial, message-waiting lamps, speakerphone, call logging, speed dial, etc. In addition to the flashing lamp call indications, call status information may be displayed on the telephone.

Automatic line selection: When the user picks up the phone, an outgoing line is selected automatically.

Bridged call appearance: The same extension number can be terminated on multiple phone sets.

Call drop: A call can be terminated without hanging up the receiver.

Call forwarding: Users can forward their calls to another station in the system.

Call park: This feature places a call in a parking orbit so it can be retrieved from any telephone in the system.

Call transfer: An incoming or outgoing call can be transferred to another user.

Callback: If someone transfers a call to an extension that does not answer after a set number of rings, the call returns to the original station.

Camp-on: Users or the attendant can send an external call to another telephone even if it is busy. The callee hears a faint camp-on tone. When the user hangs up, the camped-on call rings at the station.

Conferencing: Stations can bridge two or more lines together for a multiparty conversation.

Distinctive ringing: Different ringing tones enable users to distinguish between internal and PSTN calls.

Do not disturb: Users can press a button that silences the bell and prevents intercom calls from reaching the station.

Forward all calls: Users can redirect all calls to another station or destination.

Forward on busy or no answer: Users can redirect calls to another station or destination if the line is busy or does not answer.

Held-line reminder: After a call has been left on hold for a specified period, the telephone emits a warning tone.

Missed-call indicator: A list of unanswered calls is displayed on the telephone.

Music on hold: While a call is on hold, music or a promotional announcement is played.

Mute: A mute button on the telephone disables the microphone.

Paging: Stations can page over the telephone speaker.

Privacy: Prevents other stations from picking up a line that is in use. In some systems privacy is automatic unless the user presses a privacy release key.

Station restriction: Stations can be assigned to different classes of service for restricting long distance calls.

Voice call: A user can place a call directly to the speaker of another user’s telephone.

Volume control: The volume of the handset, speaker, and ringer can be adjusted.

Caller ID can be provided in some key systems using one of two methods. With analog lines, callers are identified with the ADSI protocol. Some key systems support BRI ISDN, which is also capable of caller ID. In either case, the call identification extends to the station display when the call is transferred. Voice mail is readily available in key systems. Since DID is not a key system feature, calls are either transferred to the user’s voice mail manually, or an auto attendant prompts the caller to dial by name or extension number.

Key systems are often used across Centrex lines to provide features that require dial-access codes on POTS telephones. Many LECs offer lines with Centrex-like features such as transfer, conferencing, and third-party add-on. These features are activated by sending a momentary on/off hook flash toward the central office to signal for second dial tone. Flashing the switch hook of a key system telephone signals the KSU to return second dial tone from the key system, not from the central office. Therefore, most key systems provide a feature button, typically called “flash” or “link” to flash the PSTN line. This feature is essential in any

key system that is intended to work behind Centrex. PBXs rarely provide this feature because they are intended to interface trunk-side connections in the central office, and these do not respond to switch hook flashes.

PBX FEATURES

This section discusses the main features that most PBXs and many hybrids, both TDM and IP, support. These features are in addition to the key system features discussed in the previous section. Two features on the key system list, flash and paging, are generally available on hybrids but unavailable on PBXs. Although the

features in this section are common to most PBXs, users will find operational differences among products. There are also differences in whether the features are standard or an extra-cost option.

Direct Inward Dialing (DID)

DID offers station users the ability to receive calls from outside the system without going through the attendant. The LEC’s central office contains a software table with the location of the DID trunk group. When a call for a DID number arrives, the central office seizes an idle trunk and outpulses the extension number, usually with DTMF tones or over a channel. DID is effective in reducing the load on PBX attendants. It also enables users to receive calls when the switchboard is closed. DID is provided on both analog and digital trunks. On analog trunks a separate trunk group is required. Digital trunks may be provisioned as tie lines between the PBX and the central office to provide two-way DID. PRI trunks offer call-bycall service selection, enabling any trunk to be used for any purpose.

Automatic Route Selection (ARS)

Most PBXs terminate a combination of public switched and private trunks on the system. For example, in addition to local trunks, the PBX may terminate T1/E1 lines to the IXC, FEX lines, and tie trunks to another PBX. Educating users about which service to use is impractical, particularly as rates vary with time of day and

terminating location, and the dialing plan varies with the type of service. It is a reasonably simple matter, however, to program route selection into the central processor of the PBX. With ARS, sometimes called least-cost routing (LCR), the user dials the number and the system determines the preferred route and dials the digits to complete the call over the appropriate trunk group. The most sophisticated ARS systems can screen calls on the entire dialed number, but some simple systems, typical of hybrids, can screen on only the NPA and prefix. The ability to screen on the entire number is important for many companies.

With it, for example, it is possible to allow users to dial some 900 numbers, but deny others. If a company has an IP gateway that enables it to call other company numbers in an overseas location, the ARS can route those calls to the gateway, and domestic calls to the PSTN. ARS can also select the trunk group based on class of service. One class could call internationally only over IP trunks, while international calls for another class always use the PSTN.A related issue is digit insertion and deletion. Some services, such as FEX, may require the PBX to insert or delete an area code for correct routing. Telephone service is easiest for users if they always dial the same way regardless of the route the call takes. For example, if the PBX has FEX trunks to another area code, the user would dial the area code, but the PBX would strip it off before passing the digits forward to the FEX trunks if the central office does not require all 10 digits. Users cannot be expected to understand the logic of this arrangement.

Networking Options

Most PBXs offer networking options, which allow multiple PBXs to operate as a single system. Networking is available on most PBXs, but it is rare in hybrids. Call-processing messages pass between PBXs over a separate data channel using IP messages or some form of common channel signaling. With the networking

option, call-processing information such as a station’s identification and class of service travel across the network to permit features to operate in a distant PBX as they do in the local system. This feature is known as traveling class mark. The objective of networking is to provide complete feature transparency, which is the ability of users to have the same calling features across the network as they have at the main PBX. For example, users want to be able to camp on a busy station, regardless of whether it is in their PBX or in a distant system, and

they want to share a voice-mail system across the network. Some features do not work across a network in some products. Call pickup, for example, enables a user who hears a ringing telephone to press a button and bring the call to his or her telephone. The lack of this feature across a network is usually unimportant since

users are normally in separate locations and cannot hear the bell. Some companies,however, start with separate systems in separate locations and later merge them. The PBXs are collocated in the same equipment room and remain networked together. If features such as call pickup do not work across the network,

users in one work group must be assigned to the same switch, which often requires moving people from one PBX to another and possibly changing numbers. TDM and IP PBXs have significant differences in the way they implement networking. Figure 24-1 illustrates some of the differences. In the top half of the figure three TDM switches are used. Each switch has a unique number range from a different central office and a local trunk group to that office. The database in each switch contains the details on each number range in its domain. Its ARS knows which trunk group to use to reach an extension in either of the other switches, but it does not contain the translations for the stations in the other switches. The IP configuration, by contrast, has three servers, each with an identical database. If one of the servers fails, the other servers can support its stations, which are attached directly to the LAN behind the routers. Each server has direct access into the IP network, but the connectionless nature of IP enables any switch to set up a path to either of the other switches. This configuration provides survivability that the TDM model lacks. It also enables users to move between switches while retaining their telephone numbers.

QSIG

TDM PBXs use a proprietary protocol similar to ISDN for networking between their own products, but networking with switches of another manufacturer is impractical. The QSIG protocol, named after Q.931 ISDN signaling, is designed to support feature transparency and sharing of common resources such as voice mail between disparate products in a private integrated services network (PISN). The official ISO name for the protocol is private signaling system No. 1 (PSS1). QSIG separates the bearer channels from the signaling, which uses a separate packetbased signaling channel. QSIG can also be used with VoIP, where it offers the advantage of potentially reducing the number of hops needed for a call.

The first layer of the protocol is called QSIG basic call, which supports transparency between multivendor nodes. All products that claim QSIG compliance must support basic services. The BC feature set is intended for call control, but a higher layer known as QSIG generic function (GF) or QSIG supplementary services supports additional services such as calling line identification. QSIG capability is important for users with PBXs from different manufacturers to network them together. QSIG support is rarely found in hybrids.

Station Restrictions

An important feature of every PBX is its ability to limit the calling privileges of selected stations. Even companies that leave employees’ extensions unrestricted normally require toll-restricted telephones in public locations such as waiting areas and lunchrooms. The type of restriction varies with manufacturer, but it is

possible with most systems to restrict incoming, outgoing, and any type of long distance. One class of employee could be given international access, for example, while others are restricted to domestic calls. Some systems can restrict down to a specific telephone number. All restriction systems should be able to restrict

selected area codes and prefixes. Area code restriction is necessary to prevent users from calling certain chargeable numbers, such as 900 numbers and to certain area codes that are known destinations for toll thieves.

Many systems provide an override feature that enables a user to dial an access code and identification number. This removes the restriction from a phone for the current session, and restores it when the call terminates. Another common feature is time-of-day restriction, which leaves phones open during working hours, but restricts them after hours.

Follow-Me Forwarding

With the increasing importance of telecommuting, several manufacturers are offering this feature, which allows the user to receive telephone calls at home, on a cell phone, or in a remote location such as a conference center. The user keeps the PBX informed of his or her location, and the PBX forwards calls accordingly. With caller ID and the appropriate programming, the system can screen calls as well, and forward calls from only selected users. Forwarding can be selective depending on time of day and day of week. At the user’s option, the system can be programmed to ring to different destinations simultaneously or sequentially in patterns that can be changed for different days or times. This feature is available from both TDM and IP systems, usually as an extra-cost option. It requires a central server that typically is accessed with a browser over the Web or a private IP network. The protocol is usually proprietary on TDM systems and either proprietary or SIP in IP systems. The most effective products link the application to an electronic calendar.

When a user is available via e-mail, some applications can download voice mail as e-mail file attachments that the user can play back on a laptop computer. This is usually a feature of unified messaging (UM), which is discussed briefly later in this chapter and in more detail in Chapter 29.

Call Detail Recording (CDR)

This feature, sometimes known as station message detail recording (SMDR), in combination with a call accounting system provides the equivalent of a detailed toll statement for PBX users. Many businesses require call detail to control long distance usage and to spread costs among the user departments. The CDR port is a serial connection that outputs the raw call details in ASCII using a proprietary field format. A call accounting system, which is discussed later in this chapter, connected to the serial port parses the detail, rates the calls, and formats various management reports such as budgetary detail and individual toll statements.

Voice Mail

Voice mail (see Chapter 28) is available as an optional feature of all PBXs and hybrids and is one that is almost invariably applied. When a station is busy or unattended, the caller can leave a message, which is stored digitally on a hard disk. The station user can dial an access and identification code to retrieve the message. Most voice-mail systems include automated attendant, an option that enables callers with a DTMF dial to route their own calls within the system. Incoming calls are greeted with an announcement that invites them to dial the extension number if they know it or to stay on the line for an attendant. Most voice-mail systems also support dial by name for callers who reach the automated attendant and do not know the extension number.

Dialed Number Identification System (DNIS)

Offered by IXCs along with T1/E1-based toll-free services, DNIS provides the equivalent of DID for toll-free calls. If multiple toll-free numbers are terminated on the same switch, DNIS digits are sent with the call to identify the number dialed to the PBX so it can route the call to the appropriate station or group. DNIS enables an organization to have several toll-free numbers and to route each call to a different station, UCD or ACD hunt group, voice mail, or any other destination within the PBX. For example, if a company has different ACD groups for sales, service, and order inquiry, it can assign each of these groups a different toll-free number and use DNIS to route the calls appropriately. This alternative is often more effective than using an auto attendant to answer the call and offer a menu of choices.

Direct Inward System Access (DISA)

The DISA feature enables external callers to dial a telephone number and password to gain access to PBX features. The DISA port can be restricted to limit calls to internal extensions, tie lines, local calls, or any other restriction level used in the PBX. If the DISA port is unrestricted, callers can gain access to long distance services. DISA helps reduce credit card calls by enabling users outside the PBX to access low-cost long distance services.

Security is an obvious problem with DISA. It is one of the most prevalent targets for toll thieves, who use it to place calls at the company’s expense. The best practice is to disable DISA. If it must be used, managers should change the password frequently and check the call accounting system for evidence of misuse.

N × 64 Capability

With the growth of video conferencing, it is often desirable to dial more bandwidth than an ordinary BRI connection provides. Conference-quality video usually requires at least 384 Kbps, which is six 64 Kbps channels. A PBX with N × 64 capability enables the user to dial as many channels of contiguous bandwidth as required.

Centralized Attendant Service (CAS)

CAS enables attendants at one location to handle attendant functions for remote PBXs over a network. Although each PBX has its own group of trunks, all calls routed to the attendant flow to the centralized location over the network. The attendant can terminate the call to any station or hunt group. A related feature is release-link trunk, which enables the PBX to release the attendant trunk after setting up the call. Without this feature the trunk is tied up for the duration of the call.

Power-Fail Transfer

Unless a PBX is configured to run from batteries or from an uninterruptible power supply, a commercial power failure will cause the system to fail. The power-failtransfer feature connects central office trunks to standard DTMF telephones. Since most PBXs require ground-start trunks, provisions must be made to operate from loop-start telephones. This can be accomplished by two methods: use a separate loop-start-to-ground-start converter or equip the telephones with a ground start button. The former method is prevalent.

Power-fail transfer is an inexpensive and effective way to obtain minimum service during power failure conditions. Even users of systems with battery backup or UPS should consider power-fail transfer to retain some service if the PBX itself fails. Some manufacturers offer power-fail transfer for digital or ISDN trunks, which can enable the owner to avoid analog trunks.

Automatic Call Distribution (ACD)

ACD enables PBXs to route incoming calls to a group of service positions. Typical applications are sales and customer service positions. Incoming calls route to an agent position based on logic programmed into the switch. Calls can be routed based on the toll-free number that was dialed using DNIS. The caller’s telephone

number may be delivered by the network and used to route calls, or an automated attendant or call-prompting software in the switch can prompt the caller to select from a menu of routing options. When agent positions are idle, the call routes to an agent immediately. If all positions are occupied, the ACD holds calls in queue and notifies the caller by recorded announcement that the call is being delayed. Calls can be overflowed to

other agent groups, routed to voice mail so the caller can request a callback, or handled in a variety of different ways, which Chapter 27 discusses in more detail. ACD is one of the most important features in a PBX, and is included in more than three-fourths of the systems shipped.

Uniform Call Distribution (UCD)

UCD distributes calls evenly among a group of stations. When one or more active stations are idle, incoming calls are directed to the station that is next in line to receive a call. When all stations in the UCD group are busy, incoming calls are answered with a recording and held in queue. When a UCD station becomes idle, the call that has been in queue the longest is directed to the station. In many UCD systems, a station user can toggle between active and inactive status by dialing a code or pressing a feature button. Compared to ACD, UCD is unsophisticated, lacking the supervisory, management, and reporting features that an ACD offers. Chapter 27 discusses UCD further.

Unified Messaging

This feature, which is discussed in more detail in Chapter 29, integrates the PBX with voice mail, fax, and e-mail so that messages can be viewed and handled on a PC screen. The feature may also enable users to translate messages from one format to another. For example, e-mail messages may be read in synthesized voice if the user is calling from a telephone and wants them read out. Eventually, with improvement in speech-to-text software, voice-mail messages will be converted to e-mail or fax. Currently, speech to text enables users to speak limited commands to read, forward, and delete voice mail messages from a telephone.

Emergency Service Interface

Most of the developed world has adopted a special dialing code such as 999 or 911

for universal access to emergency services. The basic service enables the PSAP to hold up the line so it can be traced in case the caller is unable to report the address of the emergency. Enhanced emergency services contain a database that associates telephone numbers with street addresses. The street address is often not a fine enough distinction, however. Users who dial the emergency code from hotels, apartments with a shared-tenant PBX, campuses, and multibuilding developments and the like may be difficult or impossible to locate. Therefore, a trend is toward reporting the station identification to the PSAP so it can be associated with the room number or building name. The service is known as private system automatic line identification (PS/ALI). The PRI feature in most PBXs can relay the station identification to the LEC, which passes it to the PSAP. PBXs lacking PRI can use a CAMA trunk as an alternative. The need for this feature is particularly acute

in PBXs with remote switch units that can be located in a different PSAP’s jurisdiction from the host PBX. In this case, a separate trunk group to the local central office is usually provided. The ARS is programmed so it always seizes a local trunk when the emergency code is dialed from a station served by the remote.

A related feature that is important in any large PBX is the ability to route emergency calls simultaneously to the console attendant or a security position. The law requires that the call route directly to the PSAP, but management wants to be informed of any such call. It is also a useful feature in hotels, campuses, schools, hospitals, and other organizations where people may place emergency calls inadvertently or as a prank.

Multitenant Service

PBXs that provide service to users from different organizations can use multitenant software to give each organization the appearance of a private switch. Multitenant service is a software partition in the PBX. Separate attendant consoles can be provided, and each organization can have its own group of trunks and block of numbers.

Property Management Interface

Hotels, hospitals, dormitories, and other organizations that resell service often connect the PBX to a computer to provide features such as checking room status information, disabling the telephone set from the attendant console, and determining check-in or check-out status. The PBX provides information to the computer, and accepts orders from the front desk via computer terminal. The PMI is a specialized type of computer-telephony integration (see Chapter 27).

Uniform Dialing Plan (UDP) UDP software in a multi-PBX network enables the caller to dial an extension number and have the call completed over a tie line network without the caller’s being concerned about where the extension is located. The PBX selects the route and takes care of station number translations. UDP software is effective only among PBXs of the same manufacture although it can work with QSIG-compatible PBXs if they are so equipped.

Simplified Message Desk Interface (SMDI)

SMDI is a standard way of interfacing a switch to peripheral equipment such as voice mail. The voice mail connects to the PBX over analog ports or line-side T1 and to the SMDI with a serial connection. For a call going to a messaging unit such as voice mail, the SMDI link indicates the port the call is using, the type of call, information about the call such as the source and destination, and the reason the call is forwarded such as busy or no answer. The SMDI is an open protocol for interfacing voice mail to the switch as an alternative to the manufacturer’s proprietary interface.

PBX Voice Features

As all PBXs are designed for voice switching service, they have features intended for the convenience and productivity of the users. Not all the features listed below are universally available, and many systems provide features not listed. This list, in addition to the key system features discussed earlier, briefly describes the most popular voice features found in PBXs.

Automatic call trace: Harassing or nuisance call can be traced to the origin by dialing an access code.

Call blocking: Users can selectively block calls such as specific extensions, numbers, or calls from particular trunk groups.

Call coverage: Users can have one or more coverage paths to direct how calls route when the called station is busy, does not answer, or is in do-not-disturb status. External calls can take a different path than internal calls.

Executive override: This feature allows a station to interrupt a busy line or preempt a long distance trunk.

Forced account code: On long distance calls, this feature prompts callers to enter an identification code, which is registered on the CDR. It is often used in colleges and universities where roommates share the same extension number. Many professional organizations use account codes to allocate calls to clients.

Hoteling: A station user can temporarily move to another location, log in, and have station features including the extension number follow to the new location. Intervention from the administrator is not required.

Paging access: The PBX can be equipped with paging trunks that connect to an external paging system. The trunk is reached by dialing an extension number or trunk access code. Zone paging, which allows paging in specific locations rather than the entire building is available on most systems.

Personal call routing: Users can define routing of incoming calls based on variables such as time of day, calling number, etc.

Portable directory number: Allows a user on a networked PBX to move from one switch to another without changing the telephone number.

Priority ringing: A distinctive ring is used for calls from specified numbers.

Recorded announcements: This feature provides announcements for vacant and disconnected numbers.

Trunk answer any station: This feature allows stations to answer incoming trunks when the attendant station is busy.

Whisper page: A user can bridge into a call and speak to the local user without the other end hearing.

Attendant Features

Most PBXs have attendant consoles for incoming call answer and supervision. The attendant can also act as a central information source for directory and call assistance. The console is either a specialized telephone instrument or a PC running a console program. The latter is increasingly popular because it can be easily integrated with a directory. The following features are important for most consoles and represent only a fraction of the features available.

Attendant controlled conferencing: Attendant can set up multiport conference calls.

Automatic timed reminders: Alerts the attendant when a called line has not answered within a prescribed time.

Busy lamp field: When the station is busy or in do-not-disturb mode, an LED associated with the station is lighted.

Direct station selection (DSS): Allows the attendant to call stations by pressing an illuminated button associated with the line. The line button shows busy or idle status.

Directory features: Attendants with PC-based consoles may be able to search by first and last name, department, and extension.

Night service: Calls are automatically transferred to an alternate destination when the console is closed. In many systems this feature is sensitive to time of day and day of week.

System Administration Features

System administration is a costly element of every PBX, so features that ease the administrator’s job are valuable. The following are some of the more popular features.

Automatic set relocation: Allows users to move their telephones from one location to another without the need to retranslate. The administrator gives users a code and instructions to carry the set to the new location, plug it in, and dial the code. When this is complete the system moves the station translations to the new port. This feature is inherent with IP systems, which may enable a user to log in from any available Ethernet port.

LDAP synchronization: Enables the system to update its PBX and voice mail database from customer’s LDAP directory. Eliminates or reduces redundant database entries. The application may also permit the administrator to work translations in software in advance, and then upload them to the PBX.

Network move: Similar to automatic set relocation, this feature works across a network, where automatic set relocation works only in the same PBX.

CALL ACCOUNTING SYSTEMS

All PBXs, most hybrids, and many key telephone systems include a CDR port that receives call details at the conclusion of each call. The call details can be printed or passed to a call accounting system for further processing. The CDR output of most systems is of little value by itself because calls are presented in order of completion and lack rates, identification of the called number, and other such details needed for control of long distance costs. Call accounting systems add details to create management reports, a complete long distance statement for each user, and departmental summaries. The primary purposes of a call accounting system are to discourage unauthorized use and to distribute costs to users. They also have other uses in some companies. For example, a supervisor may use the CDR record to check the effectiveness of an employee’s outgoing sales calls. Most call accounting systems on the market are software programs for PCs. CDR data either feeds directly into an on-line PC or it feeds into a buffer that

stores call details until it is polled. A buffer makes it unnecessary to tie up a PC in collecting call details. If the power fails, the battery backup in the buffer retains the stored information. In multi-PBX environments, a networked call accounting system may be required. These systems use buffers or computers to collect information at remote sites and upload it to a central processor at the end of the collection interval. If long distance calls can be placed from one PBX over trunks attached to another, a tie line reconciliation program may be needed. The tie line reconciliation program uses the completion time of calls to match calls that originate on one PBX and terminate on trunks connected to another. Networked PBXs send originating station identification over the signaling channel to a remote PBX. If the remote PBX is equipped to extract the calling station identification from the network and associate it with the CDR output, the need for tie line reconciliation is eliminated. Most PBXs can output to the CDR port any combination of long distance, local, outgoing, and incoming calls. The amount of detail to collect is a matter of individual judgment, but sufficient buffer and disk storage space must be provided to hold all the information collected.

CALL ACCOUNTING APPLICATION ISSUES

Application information for PBXs and key systems is included in the next two chapters. This section covers application information for call accounting systems.

Call Accounting Evaluation

Most PBXs today are purchased with a call accounting system that is normally programmed and supported by a third-party manufacturer. The following are some criteria for selecting a call accounting system.

Reports

The main reason for buying a call accounting system is for its reports. Evaluate factors such as these:

-What kinds of special reports are provided? Do they meet the organization’s requirements? Examples are unused extensions, long or short duration calls, unused trunks, and calls to emergency numbers.

-Can reports be distributed over the Internet or a company intranet?

-Can users access their reports with a browser?

-Are custom-designed reports possible?

- Is it possible to export report information to an external program, such as a spreadsheet or database management system, to produce custom reports?

-Are traffic reports produced? If so, are they accurate?

-Are management reports, such as inventories, provided?

-What kind of manual effort is needed to produce reports? Does it require a trained operator, or can clerical people perform the month-end operations with little or no formal training?

-Is tie line reconciliation required? If so, does the manufacturer support it?

Operational Issues

Most call accounting systems are not completely automatic. The functions required are downloading the call data from buffers (if they are used), rating calls, and producing end-of-period reports. The most effective systems provide dragand-drop capabilities for setting up and scheduling reports and distributing them to users.

Features

Many call accounting systems provide features that are of extra value. Common features are toll fraud alerts, telephone directory, and equipment inventory. Some high-end systems offer telemanagement packages, which typically include service orders, repair, and inventory in addition to directory and call accounting.

Vendor Support

As with most software packages, vendor support is important for installing and maintaining the system. Evaluate the vendor’s experience in supporting the package. Determine whether the vendor has people who have been specifically trained. Evaluate the amount of support the package developer has available and what it costs. Some vendors sell ongoing support packages, and where these are available, the cost-effectiveness should be evaluated.

Call Rating

Most call accounting packages have call-rating tables based on V&H (vertical and horizontal) tables. These divide the United States and Canada into a grid from which point-to-point mileage is calculated. Tables must be updated regularly as rates change. Also, consider that many companies do not need absolute rate accuracy. To distribute costs among organizational units, precision is usually not required. Many long distance rate plans use rates that are not distance sensitive, so V&H rating accuracy is not required. The rating tables identify the called location, so if rating tables are not used, the called city and state will not be printed on toll statements unless the vendor offers an abbreviated table. Determine facts such as these:

-What kind of rating tables does the manufacturer support?

- How frequently are tables updated?

- What do updates cost?

- What IXCs’ rates does the package support?

- How are intrastate rates calculated?

- Do you need to bill back to user departments with high accuracy?

Capacity

Call storage equipment is intended to maintain information on a certain number of calls. When buffer storage is full, it must be unloaded and calls processed. Usually, the system must store at least 1 month’s worth of calls. Evaluate questions such as these:

-How much storage space is required?

-What is the capacity in number of calls, both incoming and outgoing?

-How much growth capacity is provided?

-Is storage nonvolatile, so if power fails calls are not lost?

Gray FullbusteR

Tuesday, January 4, 2011

Wednesday, December 15, 2010

New words

Sunday, December 12, 2010

Chapter 24

Миний орчуулах арга

My Translation methods

My Reading strategies

Reference letter

Сэтгэгдэл

zarlal

Таны IP