I have a UCM6510 works as Call-Center and office phone also. Maximum concurrent calls is about 20~25 (all types)
We receive about 1000 - 1500 calls a day from our customers. But 10% is failed call.
Most of failed call in which customer can not hear anything. UCM6510 IP is 10.163.2.182. And the SIP Provider server IP is 10.163.201.4
I am using network troubleshooting tool on UCM6510 to capture packet on interface connect to SIP provider, then i see that for failed calls, UCM6510 doesn’t send SIP 200 OK after sending “trying” message.
I m using the newest firmware 220.127.116.11