3CX is a free VOIP / SIP phone software. You can use your PC as a phone. Works with any SIP / VOIP provider / phone service. Use this instead of the soft phone provided by your VOIP provider which locks you into their VOIP phone service. Easy to use interface includes dial pad and buttons to transfer or forward a call. Set-up conference calls with a few mouse-clicks. Includes call log, phone-book, call status & statistics and more.