SJPhone – VOIP for PowerPC

SJphone® is a VOIP softphone that allows you to speak with any other softphone running on a PC/PDA, any stand-alone IP-phone, or using Internet Telephony Service Provider (ITSP) with any traditional wired or mobile phone. It supports SIP and is fully inter-operable with most major VOIP vendors and ITSPs.

* http://www.sjlabs.com/sjp.html