chapter24

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.