PRI problem... couldn't be chan_sip.c... or could it?

I have been having a problem where the PRI b-channels appear to lock up with no alarm or irq conflicts. The d-channel still seems to work so the phones will ring but no audio (the workers love that!). Inter-office calling is not affected. If you unplug either PRI connection and re-plug it the connection audio comes right back. Verizon ran a trace and all was cool on their end and my logs only have one error (but I had it like 25,000 times yesterday) but it seems unrelated. Does anyone know what the following warning means?

WARNING[28587] chan_sip.c: SUBSCRIBE failure: no Accept header: pvt: stateid: -1, laststate: 0, dialogver: 0, subscribecont: ‘’, subscribeuri: ‘’

I can not find this anywhere! I would be very grateful for any help.

Link to original post that got me thinking there may be a cnnection…

Asterisk 1.4.26
FreePBX 2.4
2 Verizon PRI spans
50 Polycom SIP phones


What’s terminating the PRI?

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