- Gold, 750 points or more
Cisco Designated VIP,
2017 IP Telephony
Recently we have replaced legacy SIP server with Cisco SME after that users observed that, Caller doesn’t get busy notification if called phone is busy, instead they get “congestion” notification.
Below is the Call flow:
Alcatel Callmanager 1---SIP Trunk----Cisco SME----SIP Trunk----Alcatel Callmanager 2
I have analyzed SIP logs and found that Cisco SME doesn’t relay “Buys here, 486 message” back to Originator callmanager, in above scenario when someone call from Alcatel Callmanager 1’ phone to Alcatel Callmanager 2’ phone (which is Busy, already on call). In this case Alcatel Callmanager 2 sends “Busy here, 486 message” to Cisco SME and Cisco SME sends ACK message back to it but Cisco SME doesn’t relay this message back to Alcatel Callmanager 1, and after few seconds Alcatel Callmanager 1 sends “CANCEL” message to Cisco SME and then Cisco SME ACK to it and sends “Cancelled request” to Alcatel Callmanager 1 .
I'm attaching the Cisco SME SDI logs and below is the info..
From: 10.205.39.8 (Alcatel Call manager 1 IP address)
Caller Phone: 6206698
To: 10.205.228.9 (Alcatel Call manager 2 IP address)
Called Phone: 6109565
Time stamp: 11:53:36
Why Cisco SME is misbehaving ?
Please let me know if moer information required.
Thanks in advance !!!
I will advise to schedule a time to test the secondary alcatel server by removing the primary sip trunk from the RG. I am sure that this server is not working or the connection to it is not working.
The service parameter is used for H323 gateway redundancy purposes especially with E1 circuits. E,g. When you have a two H323 gateways configured with E1s. When the E1 on the primary gateway goes down, the gateway will send a user busy flag to CUCM. When CUCM receives this, what it will do next depends on what this parameter is set to. If it is set to "TRUE", then cucm will drop the call, if it is set to "FALSE" then CUCM will send the call to the secondary gateway in the RG.
This behaviour is similar with CUBEs and SIP trunks. When CUCM receives a 486 user busy or 401 unallacated or un assigned number, it will use this parameter to determine what it does next.
This parameter was built into the SIP stack in CUCM to allow for redeundancy purposes as well. e.g. Supposing you have multiple cluster in your environment and in your RG, you have configured two sip trunks, one to the first alcatel cluster and the second to another alcatel cluster. When calls to the first cluster receives busy, this will allow SME to send the call to another cluster.
I believe it is safe to say that you can leave this parameter set to True, fi all you have is a SIP trunk. I dont see a need for SME to try and send a call that was either rejected by the end user or busy to another place
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