So I am having an issue with a customer. They have a NV6240 emulating 2 PRIs. When they have maxxed out their channels the 6240 is sending a 404 not found anywhere back to the SIP Provider who in turn is sending a redirect to the caller stating "This number has been disconnected." I would like to change the SIP header instead of a 404 to basically send a busy signal. Anyone ever done this. I looked at the SIP Manipulations document here and couldn't find anything. If anyone has ideas on how the config should look please let me know. If more information is needed please ask as well.
You can do this by mapping the ISDN cause code to the SIP response. The cause code for no channel available should be cause 34, but it might be something else such as cause 26 or 44. I would try the following command:
voice cause-code-map from-pri 34 486
This will cause the Adtran to send a SIP 486 (user busy) when it gets a cause 34 (no circuit/channel available) from the PRI.
If this doesn't fix it, do a "debug isdn l2-f" and place a call when all channels are in use to see what ISDN cause is sent and map that to SIP 486 in a similar manner.