oozenoz

Personally, I would not consider what Avaya did as a 'work around' - nor would I call it a 'fix.' I would say they modified the premise switch to conform to what the network was expecting.

When the network switch sends a SETUP message over the PRI, the valid (non-clearing) responses are CALL PROCEEDING, ALERTING, and CONNECT messages. (source: AT&T ISDN Primary Rate Interface Specification, 1995) If none of these are received before the network switch timers expire, the call will be torn down. From this point of view, AT&T was correct in their analysis of the issue because your premise switch was not providing what the network switch was expecting - within the proper timeframe. I have a suspicion that the premise switch was treating the redirection/forwarding as interworking, because PROGRESS is sent when interworking is involved, but not providing the CONNECT message until the far end of the redirect actually answered if it was going to provide answer supervision at all.

I hate to repeat myself, but all network switches are not created equal. The premise and network switches must be talking the same language in order for services to work properly. Blame who you will when they do not.

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- calvin