How do I enable call waiting on FXS ports on 2431 IADs? I tried several different configuration commands and they either do not apply to the chassis or do not seem to work. I am running IOS 12.4(24)T1. Are there SIP message constraints? The device receives secondary INVITE messages sent from the proxy on active calls and responds with 100 and 180 messages, but these do not translate to CW activity on the FXS ports.
I stand corrected. See link for supplementary features on FXS ports with SIP server.