I have been battling this for awhile at a customer site. Site has IP office R9.1.7. I have the same setup at my office using same sip provider and same release of ip office with no trouble. The sip provider recently changed to a new peering sip server. I believe this is the trouble. I pointed my customer's sip trunks to my office and internet and my sip trunks work and my customer does the same thing with the drop after 32 seconds. I called the provider and they did not have a reason why. They say they see back and forth 200 messages then a bye message. I have attached a monitor trace of the dropped call. Any help would be greatly appreciated.