Free and open-source license
A SIP server, also known as a SIP proxy, manages all SIP calls within a network and takes responsibility for receiving requests from user agents for the purpose of placing and terminating calls.
Proprietary license
- 3Com VCX IP telephony module: back-to-back user agent SIP PBX
- 3CX Phone System, for Windows, Debian 8 GNU/Linux
- Aastra 5000, 800, MX-ONE
- Alcatel-Lucent 5060 IP Call server
- Aricent SIP UA stack, B2BUA, proxy, VoLTE/RCS Client
- AskoziaPBX
- Avaya Application Server 5300 (AS5300), JITC certified ASSIP VoIP
- Bicom Systems IP PBX for telecoms
- Brekeke PBX, SIP PBX for service providers and enterprises
- Cisco SIP Proxy Server, Cisco unified border element (CUBE), Cisco Unified Communication Manager (CUCM)
- CommuniGate Pro, virtualized PBX for IP Centrex hosting, voicemail services, self-care, ...
- Comverse Technology softswitch, media applications, SIP registrars
- Creacode SIP Application Server Real-time SIP call controller and IVR product for carrier-class VoIP networks
- Dialogic Corporation Powermedia Media Servers, audio and video SIP IVR, media and conferencing servers for Enterprise and Carriers.
- Dialexia VoIP Softswitches, IP PBX for medium and enterprise organizations, billing servers.
- IBM WebSphere Application Server - Converged HTTP and SIP container JEE Application Server
- Interactive Intelligence Windows-based IP PBX for small, medium and enterprise organizations
- Kerio Operator, IP PBX for small and medium enterprises
- Microsoft Lync Server 2010 & 2013
- Mitel Communications Director
- NEC SV7000 back-to-back user agent SIP PBX
- NEC UNIVERGE 3C Unified Communications and Collaboration software
- Nokia Siemens Networks hiQ8000
- Nortel SCS500
- Nortel SIP Multimedia Communication Server 5200
- Objectworld UC Server
- Oracle Communications Converged Application Server (OCCAS)
- Oracle WebLogic SIP Server
- Spirent SIP Server Platform
- ShoreTel IP phone systems with unified communications and contact center built in
- Snom One free/blue/yellow (Snom acquired and renamed pbxnsip) (SIP)
- Speedflow Communications VoIP class 4/5 softswitches with integrated billing, transcoding, SIP-H.323 converter.
- Sterlite Technologies Neox IPPBX, IMS - ISC, Dial Center - OmniChannel Call Center, IVR products
- Sun Microsystems Sun GlassFish Communication Server
- Tadiran Telecom Coral Ipx family and Aeonix softswitch
- Tandberg Video Communication Server - SIP application server, media server and H.323 gateway
- Unify OpenScape Voice, OpenScape 8000 SIP softswitch, mediaserver, ... (SIP)
- Voice Elements Inventive Labs' .NET Voice Development software and SIP stack platform.
- Zultys MX250/MX30 IP PBXs for SMB and enterprise