Public voice networking

Last Updated : Feb 10, 2025 |

IP Office supports a range of trunks and signaling modes for connection to the public switched telephone network (Central Office). Some of these lines are only available in certain territories; please check with your distributor for local availability. Primary rate trunks are available with either a single (24/30 channels) or dual trunk (48/60 channels).

ISDN Primary Rate (ETSI CTR4)

Service is provided by IP500V2 Universal PRI cards. ISDN Primary Rate provides 30 x 64K PCM speech channels over an E1 circuit and one signaling channel. Signaling Conforms to the ETSI Q.931 standard with Cyclic Redundancy error Checking (CRC).

The following supplementary services are supported:
Calling Line Identification Presentation (CLIP)
Provides the telephone number of the incoming call.
Calling Line Identification Restriction (CLIR)
Prevents the telephone number of the IP Office being presented on an outbound call.
Direct Dialing In (DDI)
Where the exchange provides the last x digits of the dialed number on an incoming call. This allows IP Office to route the call to different users or services.
Sub-addressing
Allows the transmission/reception of up to 20 digits, additional to any DDI/DID or CLIP information, for call routing and identification purposes.
IP Office supports the following features on both PRI and BRI trunks.
Note:

Feature availability depends on the ISDN service provider for which there may be charges.

Malicious Call Identification (MCID)

(9400, 9500, 9600, J100)

Short codes and button programming features are available so that users can trigger this activity at the ISDN exchange when required. This feature is NOT available on standard ISDN DSS1 telephones.

Advice of Charge (AOC)

(IP telephones only)

Advice of charge during a call (AOC-D) and at the end of a call (AOC-E) is supported for outgoing ISDN calls other than Q.SIG. The call cost is displayable on T3 telephones for call accounting purposes. IP Office allows configuration of call cost currency and a call cost mark-up for each user.

Call Completion to Busy Subscriber (CCBS)

(9400, 9500, 9600, J100, DECT telephones)

CCBS can be used where provided by the ISDN service provider. It allows a callback to be set on external ISDN calls that return busy. It can also be used by incoming ISDN calls to a busy user. This feature is not available on standard ISDN DSS1 telephones.

Partial Rerouting (PR)

(9400, 9500, 9600, J100, DECT telephones)

When forwarding a call on an ISDN channel to an external number using another ISDN channel, partial rerouting informs the ISDN exchange to perform the forward, thus freeing the channels to IP Office. This feature is not available on standard ISDN DSS1 telephones and it is not supported on Q.SIG.

Explicit Call Transfer (ECT)

(Typically used by a third-party application)

ECT is supported on the S0 interface. A call to an S0 Endpoint can be transferred to any other device such as an analog, digital or IP endpoint or to any trunk. The normal usage of this feature is by a third party application connected through one or more S0 interfaces to IP Office. One example is the VoiceDirector, an automatic call assistant.

ISDN Basic Rate (ETSI CTR3)

Service is provided by IP500 V2 BRI cards. ISDN Basic Rate provides 2 x 64K PCM speech channels and one signaling channel using Q.931 signaling and CRC error checking. Both point to point and point to multipoint operation is supported. Multipoint lines allow multiple devices to share the same line; however point-to-point is the preferred mode.

Basic Rate supports all the services that are supported on the primary rate version with the addition of Multiple Subscriber Number. This service is usually mutually exclusive with the DDI/DID service and provides up to 10 numbers for routing purposes, very similar to DDI/DID.

E1R2 channel associated signaling

Service is provided by IP500 V2 Universal PRI cards.

The IP500 Universal PRI card configured as PRI E1R2 supports a single or dual RJ45 network connection. Each card provides channels that can be configured for MFC, Pulse or DTMF dialing dependent on the requirements of the network.

North American T1 Primary Rate

Service is provided by IP500 V2 Universal PRI cards. T1 Primary Rate provides up to 24 64K channels over a 1.54M circuit. Each channel of the T1 trunk can be independently configured (channelized) to support the following signaling emulations with handshake types of immediate, delay or wink.

  • Loop-Start

  • Ground-Start

  • E&M Tie Line

  • E&M DID

  • E&M Switched 56K

  • DID - Channels configured for DID/DDI support incoming calls only. The carrier or Central Office will provide the last x digits that were dialed to be used for call routing.

  • Wink-Start

IP Office T1 trunks support both DNIS and ANI services, where available from the central office.
Dialed Number Identification String (DNIS)
Provides a string of digits to IP Office depending on the number dialed by the incoming caller. This string can then be used to route callers to individual extensions, groups or services.
Automatic Number Identification (ANI)
Provides IP Office with a number identifying who the caller is. This may then be used for routing or computer telephony applications.

T1 trunk cards incorporate an integral CSU/DSU, eliminating the need for an external unit. The CSU function allows the trunk to be put in loop-back mode for testing purposes. This can be set manually, using the monitor application, or automatically from a Central Office sending a Line Loop Back (LLB) pattern. The DSU function allows the T1 trunk to be shared between data and voice services.

North American Primary Rate Interface (PRI)

Service is provided by the IP500 V2 Universal PRI cards. IP Office supports Primary Rate ISDN trunks on 5ESS or DMS100 central office switches provided by AT&T, Sprint, WorldCom and other Local Telcos. Channels can be pre-configured for the supported services or negotiated on a call-by-call basis.

Special services can be configured to route calls to local operators or pre-subscribed carriers for both national and international calls (SSS). Alternate carriers can also be selected through the configuration of IP Office Transit Network Selection (TNS) tables.

IP Office also supports the Calling Name and Number service over Primary Rate Trunks (NI2).

Analog trunks

Loop start
Loop start trunks are available on the IP Office Analog Trunk cards installed within the IP Office control unit, or on the Analog Trunk 16-port expansion modules (ATM16). The first two trunks on the ATM16 are automatically switched to power fail sockets in the event of power being interrupted. Powerfail is also available on the trunk card when fitted to a combination or phone card. They conform to the TIA/EIA-646-B standard. The loop start trunks also support incoming caller line identification (ICLID) conforming to GR-188-CORE and GR-31-CORE standards. IP Office can use this information to route calls or provide it to computer applications to display additional information about the caller.
Ground start
Ground Start trunks are only available on the ATM16, configured through IP Office Manager. The first two trunks on the module are automatically switched to power fail socket in the event of power being interrupted. They conform to ANSI T1.401 and TIA/EIA-646-B standards. Not available in all territories.
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