Intermittently calls are getting dropped and not going through. Getting message "500 Server Internal Error".
This is applicable to all CM versions.
Call flow - Frequently Outbound dialer making call > CM > SM > Service provider.
Below the SIP messages for a failed call.
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192.168.xx.xx 192.168.xx.xx
*192.168.xx.xx*
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12:29:42.648 |--INVITE-->| | (186) sip:[email protected] U:91314xxx506
12:29:42.649 |<--Trying--| | (186) 100 Trying
12:29:42.654 | |--INVITE-->| (187) T:13148xxxx06 F:88xxxx3607 U:1314xxxx506
12:29:42.670 | |<--Trying--| (187) 100 Trying
12:29:42.671 | |<--Server -| (187) 500 Server Link Monitor Status Down
12:29:42.671 | |----ACK--->| (187) sip:[email protected]
12:29:42.672 |<--Server -| | (186) 500 Server Internal Error
12:29:42.682 |----ACK--->| | (186) sip:[email protected]
The dialer makes a call and reaches CM which is then forwarded to SM and to the service provider. From the trace, it can be seen that the CM received a "500 Server Link Monitor Status Down" message from the SM. By taking an indepth look into the SM logs, it was found that the SM was actually sending all the necessary messages to the far end (in this case it is the service provider, there was no SBC in customer environment), but the far end was not responding. The service provider claimed that they didn't receive any messages for the calls, but later it was found to be issue with one of the SBCs with the service provider.
