Hi! I just came in possession of a Cisco 7942 IP phone and I am eager to set it up. I did some research and discovered how to flash it with SIP firmware as opposed to the SCCP firmware. As for the actual SIP server, I discovered Kamailio and decided on this one as it is in the main package list for OpenBSD which is the platform I mainly want to develop this on. I also discovered Siremis as a GUI for Kamailio, but it seems development has been lacking. Does anyone have any tips or tricks or advice on setting up a SIP server? Anything weird I need to look out for? Any challenges you guys specifically faced when setting up a SIP server? Thank you for any tips and advice!
SIP can be very interesting / fun once you get the hang of it! I agree with other comments though that starting with a Cisco 79xx is a rough way to start. A soft phone or Cisco/Linksys SPA 9xx or any yealink phone is a great starting point.
Kamailio is also an aggressive starting point. There are several open source options that might be a bit more friendly to start with.