I have spent a frustrating amount of time trying softphones for use with SIP.
There are not many SIP resources available because it is still not widely used. Skype is the main competitor to SIP and Skype is roaring away (thanks to its ability to get around firewalls and an excellent marketing team). If you want to use SIP, here is a list of softphones. If you know of a softphone not on this list, please contact me.
The features of the programs vary considerably.
- SJPhone – Free. Lots of features.
- Express Talk – Free. Lots of features.
- iaxComm – Free.
- eyeBeam 1.5 – $45. Popular.
- X-Lite 3.0 – Free. Popular. Made by the same company that provides eyeBeam, but fewer features.
There are many services which tie you to using their SIP service. These include: