3CX SIP Server software  for Windows

3CX Phone System is a SIP server for Windows that works with popular VOIP Gateways and SIP phones to allow you to setup a complete IP PBX in a matter of half an hour. 3CX’ SIP server is quickly downloaded and installed and runs on all popular versions of Windows, including XP, 2000 and 2003 server. Configuration is performed via an easy to use Web interface. 3CX Phone System has withstood rigorous quality testing and has received Windows 2003 certification.

Download the Free Edition of 3CX SIP Server

A Free edition of 3CX Phone System for Windows is available. The free edition supports an unlimited number of extensions, while the 3 commercial editions also include support and additional features such as integration with Exchange 2007 support, fax, call queuing, call pick up and call parking, among others. All editions come with a Windows VOIP Client. Download your free SIP server today at http://www.3cx.com/ip-pbx/index.html.

Key 3CX Phone System SIP server features

  • Supports SIP 2.0
  • Supports the use of standard PSTN/Telephone lines via SIP Gateways such as Patton, Grandstream and Audiocodes
  • Supports the use of SIP Trunks and SIP providers
  • Supports main codecs including G711, GSM, IspeeX and ILBLC
  • Available as a free edition supporting an unlimited number of extensions
  • Sip SIMPLE chat is in development

The SIP Protocol

The Session Initiation Protocol (SIP) is a protocol for establishing real time communication sessions with one or more participants. Its most frequently used for Voice communications but it can handle video as well, as well as future applications. SIP was designed to be independent of the transport layer, i.e it can work on UDP, TCP or STCP. All voice/video communications take place via another protocol, usually RTP.

There are many RFCs surrounding SIP, but the most important one is RFC 3261

SIP is a text based protocol that looks and acts very much like the HTTP protocol. The original designers (Henning Schulzrinne & Mark Handley) wanted to make a protocol that had its roots in the IP world, rather then in the telecoms world. Sip has been an amazing success, being the major driver in the adoption of VOIP and Computer Telephony in recent years. All major manufacturers have adopted the standard and availability of SIP software, SIP hardware and Sip service providers is widespread.

Sip servers are responsible for setting up the calls between Sip devices. SIP servers usually combine several of the SIP server functions such as SIP proxy and SIP registar into one piece of software. 3CX Phone System is both a SIP proxy, a SIP registrar as well as a media server in order to handle real time voice communications as well.