My customer is trying to get a SPA8000 ATA (version 6.1.11) to do a SIP trunk conneciton to an AudioCodes SBC. We have the SIP trunk up and working, with lines 1-4 included in the trunk. Outbound calls from all lines in the trunk group work, and everything is great. Inbound calls, however, only succeed if the call lands on lines 1 or 2. If the call hits line 3 or 4, the ATA responds with a SIP "486 Busy Here" error and the caller gets a busy tone. We've captured this is traces and verified it in logging output on the SBC. It's absolutely the response from the ATA causing the busy.
It's reproducable 100%. If the trunk hunt order is 1,2,3,4, we can get two inbound calls, or four outbound calls, but the 3rd inbound call gets a busy. We rearranged the trunk to hunt 4,3,2,1, and we can still do 4 outbound calls but no inbound calls. If we set the trunk hunt for 1,3,2,4, we can only get one inbound call. Seemling as soon as the hunt group hits line 3 or 4, the hunt fails and the ATA responds with a 486 Busy Here message.
We set the call capacity for the trunk to unlimited, and since we can get all 4 outbound calls I'm convinced it's not call admission control or a resource depletion issue. And since the outbound calls for all 4 lines work I don't believe it's a NAT issue (we already worked through the NAT problems with lines 3-8).
Can anyone shed any light on this?
Best Regards,
Bob McCouch
CCIE #38296 (Routing & Switching)
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