3CX Phone System is a free VoIP PBX software for Windows that allows you to easily set-up a professional, modern phone system for your business. Use popular VoIP providers and SIP trunks for low cost calling. Use popular IP Phones (Polycom, Snom, Cisco & others) or Softphones. Keep using your old telephone lines with the use of VoIP gateways. Runs on Microsoft Windows - no need to dedicate a PC or learn Linux! Eliminate phone wiring. Includes enterprise phone system features such as voicemail, auto attendant, fax server, unified communications and more. 3CX Phone System FREE edition is a fully functional product - it supports an unlimited number of extensions and does NOT time out