I need to create an ISDN-PRI tandem

Asterisk Asterisk Support
1

I have an existing PBX in a data center that does EuroISDN (30B+D) to the PSTN. I need to intercept the ISDN SETUP message called party, perform a database lookup, then modify the called party address before sending it on to the PSTN. I picture a two span Digium card (TE122) where the PBX feeds into one port, and the PSTN into the other. It will act as a tandem, only modifying SETUPs and passing all other messages through unchanged.

My question is: Is this possible and has it already been done? Setting up Asterisk with two trunk groups and two separate “D” channels with a “hook” into an external application is what I imagine it would look like.

Any help is appreciated

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Asterisk is not a proxy. It will fully terminate the call on one side and generate fresh signalling on the other side. Whilst standard messages may happen to be regenerated the same, any custom messages will be lost.

1 Like
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Hi David, thank you for your quick reply. I can live with it not being a proxy. If the D channel signaling from each direction can be brought to an external helper function, that would be fine. It sounds like the SETUP from the PBX (Cd=A) would be terminated by Asterisk, who would then send to the PSTN a SETUP (Cd=B)

I’m wondering if I should just program the Digium card at a low-level?