Digital protocol - PRI feature

Avaya Logo

Digital protocol - PRI feature

Type of feature

When you use the Primary Rate Interface (PRI) digital protocol with ports on an Avaya IR, you must have WebLM licenses for each port that uses the protocol.

About the PRI digital protocol feature

PRI is an ISDN configuration that functions like an enhanced T1 circuit. ISDN is an international telecommunications standard for voice, video, and data transmission over digital lines. The system supports and can communicate with any switches that support the following digital signaling protocols:

AT&T PRI
National ISDN
NTT (INS-1500)
ETSI
Nortel PRI
QSIG (beginning with Avaya IR Release 1.3)

PRI is desirable for customers who need faster call-setup times, special signaling, or access to the information elements that are available with PRI. Such information elements as ANI, DNIS, redirecting number, and service type are available for incoming PRI calls. Outbound calls can provide information elements like outbound ANI and service type.

QSIG is an ISDN-based signaling protocol for signaling between nodes of a Private Integrated Services Network (PISN). The QSIG protocol is based on the ISDN Q.931 standard. For Avaya IR Release 1.3, the QSIG protocol supports the following features:

Obtain ANI and DNIS from incoming QSIG calls
Transfer a QSIG call using the Transfer by Join feature (as defined by the QSIG ECMA 178, June 1992 standard). This feature allows an incoming QSIG call to the Avaya IR to be transferred to another termination point outside of the Avaya IR. After the incoming call has been established, a second call is placed out to the new termination point. The two calls are then joined together in the Avaya IR system to complete the transfer.
Participate in a QSIG Path Replacement operation (as defined by the QSIG ECMA 176, June 1992 standard). The Avaya IR system does not initiate the Path Replacement request, but can pass messages between the PBXs involved in the Path Replacement operation. The QSIG Path Replacement feature optimizes the voice-connections between multiple QSIG switching sites by reducing the number of hops (trunk facilities) it takes to route a call between sites.

The Avaya IR system supports non-facility associated signaling (NFAS) across all spans on a single digital telephony card.

The Avaya IR system supports only one D-channel for each PRI interface. Avaya IR does not support a primary and backup D-channel.

Hardware requirements

At least one digital telephony card must be installed and operational.

Software requirements

The PRI digital protocol feature requires the NMS package (AVnms). For more information, see NMS package.

Application development considerations

The following considerations apply to application development for PRI:

IVR Designer. The Answer Call and Disconnect nodes and the Make_Call and Call_Bridge external functions are supported by PRI. The Call Transfer node is not supported by the PRI protocol.
TAS. Several capabilities are available to implement the PRI feature in TAS applications. The tic instruction is used for basic control of incoming and outgoing PRI calls. The tic(`C') instruction provides additional return code information for T1 interfaces.
IRAPI. The irCall(), irAnswer(), irXfer(), and irDisconnect() functions provide the basic call control capabilities for T1 interfaces. The irSetIE() and irGetIE() can be used to set and get information elements available only with PRI.

Using this feature

Administer this feature using Web Administration (Configuration Management > Switch Interfaces > Digital Interfaces) or the nms command. For ISDN-Primary Rate Interface T1 or ISDN-Primary Rate Interface E1, configure digital interfaces as follows:

Configure T1 cards with Non-Facility Associated Signaling (NFAS) or without NFAS.
When a dual port T1 card is administered with NFAS, the first trunk on the card carries the D-channel for both trunks on the card. The second trunk on the card is administered to have no D-channel. Thus, with NFAS, the card has 1 D-channel and 47 B-channels (23 B-channels from the first trunk and 24 B-channels from the second trunk).

When a quad port T1 card is administered with NFAS, the first trunk can carry the D-channel for all trunks on the card for one D-channel and 95 B-channels.

When a T1 card is administered without NFAS, both trunks must be administered to have a D-channel. Without NFAS, each trunk has one D-channel, the 24th channel of the trunk, and 23 B-channels.

The D-channel cannot be used to run applications. It carries messages between the switch and the Avaya IR system. These messages are used to control the state of calls on all the other PRI channels on the card. The B-channels (bearer channels) provide two-way audio channels to run applications. Therefore, on a PRI trunk that has a D-channel, the first 23 channels (B-channels) on that card can be used to run applications. The 24th channel (D-channel) is reserved for call control.
For E1 PRI, channel 0 is reserved for framing and channel 16 is reserved for the D channel, the remaining 30 channels are B-channels. Each E1 PRI trunk has its own D-channel. NFAS configurations are not supported for E1 PRI.