Josh Benson of Open Source Society tells us how pjsua can be used as fully featured SIP client to solve real life problems in PJSIP: Command-Line VoIP Client for Linux:
Some time ago, I was tasked at work with finding an IP telephony client that used the SIP protocol, ran on linux, and did everything from the command line. The goal was to have a program that could be deployed at remote networks to test the quality and performance of VoIP calls between the remote site and our central Asterisk VoIP server.
Josh has it spot on. While pjsua is intended primarily as the reference implementation of PJSIP (command line programs are always easier to learn than GUI), it is also intended to have the full features of a SIP client. Softphones with pretty GUI are easier to use, and they are also easier to find, but for some specific tasks, sometimes we have to revert back to using the good old console application, and that’s where pjsua fits the bill.
I’m glad that Josh and others find it useful. Thanks Josh for sharing your experience.
[Update: As the Open Source Society website is gone, I've removed the hyperlink. Sorry. Let me know if this is temporary and it's back]