Avaya PBX Trunk

Solution Integration > PBXs > BT Call Server > Example Configurations > Trunks Configuration


		The configuration for an Avaya PBX trunk is the same as for a CUCM Trunk, except for the additional setting shown below.

The Avaya PBX does not use the "From:" header the way Cisco and many other SIP PBXs do.

Instead, Avaya prefers the "P-Asserted-Identity" (PAI) header, which carries the network-asserted identity of the caller.

(typically the CLI/extension/number that Asterisk derives from the From:/CALLERID() before sending).

When PAI is absent, Avaya falls back to the "Contact:" header.

In our environment, with the newer PJSIP stack in Asterisk, the "Contact:" header no longer contains the extension/CLI but defaults to "asterisk@IP".

This is correct per SIP RFCs (the Contact is not required to match the caller identity), but it means Avaya shows “anonymous” since it is pulling identity from the wrong place.

There is no reliable way to alter the "Contact:" header in Asterisk for outbound trunk calls, nor should this be necessary, as identity is properly conveyed using PAI (when enabled).

The correct and standards-compliant solution is to enable PAI on the Avaya trunks so that Avaya receives the caller identity in the supported header

(This ensures Avaya will correctly display the caller ID without relying on Contact:.)

This setting should be added to the trunk templates for all trunks that terminate on an Avaya PBX.

endpoint/send_pai = yes ; Send the P-Asserted-Identity header


		This applies to BT Call Server v3.x and greater, which makes use of the new PJSIP stack.