Calls dropping

I have three systems version 2.11 Freepbx Distro. We inherited Escene ES410 phones. The trunks are SIP, and T1/PRI. We are experiencing random call dropping. I have captured the calls in TCPDump. and I see the packets just end. There are no messages to end the call, the packets just stop. I have contacted Escene but no reply as yet. We have installed Aastra and Yealink in these systems and they have no issues, reported. I know the Escene models passed in Aastra testing. The phones were not defaulted. The phones were OEM from another provider. I have looked into Reinvite sip and it is turned off in the system and in the phones.

Anyone have thoughts?


I have found that the system is sending Bye messages to the phones. Why would it do that ? I have the
RTP timers:
RTPtimeout = 300
RTPHoldtimeout = 300

Still looking for a solution here. The call dropping has continued, the calls are even between phones on the same network behind the firewall.

You need to share at least the complete sip debug for a failed call or better a tcpdump trace for a falied call and do not masquerade the IPs.

We were unable to get this resolved with the existing phones. We installed Yealink T26 phones and now 5 days without a dropped call. So definately a phone issue.