1)   3CX VOIP Phone for Windows 6.0
Free VOIP / SIP phone (softphone). Use your PC as a phone. Works with any SIP / VOIP provider and phone service. Easy to use interface to transfer, forward calls or review history of calls. Free download from http://www.3cx.com

 2)   3CX Phone System for Windows Free 6.0
3CX VOIP Phone System FREE edition is a SIP-based IP PBX developed for Windows. Easy to install and configure, it eliminates phone wiring and allows hot desking. Lowers call costs via VOIP providers & eliminates vendor lockin. Download FREE edition!