3CXPhone is a free VoIP phone for Windows supporting the SIP standard. You can use 3CXPhone with a VOIP provider or an IP PBX (for example 3CX Phone System or Asterisk)
Features
- Multi-line (up to 3 lines)
- Ability to transfer calls
- Record calls
- Call History
- G.711, GSM, iLBC and Speex codecs
- Supports Plantronics & standard USB headsets