The default SIP Options message header on AudioCodes equipment is using the SBC’s SIP interface IP address in both the To and From header field when sending keep-alive Options, which has been messing with my OCD over the years, but never really caused any issues.
When looking at traces in “The Monkey” it is difficult to identify the right Options message in the call list when multiple proxy sets on the same SIP interface are used as the To field is always the SBC’s SIP interface’s IP address.
So today I got a request from a customer that they wanted the the To field crafted specifically to match the IP address of the SIP entity we are sending the SIP Option to, which makes total sense in my book. We were trying to troubleshoot an issue, however this ended up being a red herring, but hey at least it will now look nice in the trace logs.
Any SIP header fix-up would normally be done by creating a message manipulation rule and associate the manipulation set id as an outbound rule on the IP Group. However after creating the rule, it didn’t take effect until another parameter was enabled on the IP Group.
Step 1. – Configure the IP Group.
In this instance I am using Outbound Message Manipulation Set 2 (which I had already defined for other manipulation rules needed). And then Enable the Proxy Keep-Alive using IP Group settings. Without enabling the setting the specific Options message manipulation rule will never take effect.
Step 2. – Create the Message Manipulation Rule.
Create the message manipulation rules with the following parameters:
Manipulation Set ID: 2
Message Type: Options
Action Subject: Header.To.URL.Host
Action Type: Modify
Action Value: Param.Message.Address.Dst.IP
After these two pretty simple steps you will now see a properly crafted Options header in the SYSLOG trace tool.
This has been a pet peeve of mine for years, but never had the time or inclination to seriously take a look at the issue until requested by a customer. I would like to extend my thanks to AudioCodes support, as I didn’t 100% solve this issue on my own.