SIP Provider UK
- SIP Provider British Telecom HSIPT (UK)
- SIP Provider British Telecom One Voice SIP Trunk (UK)
- SIP Provider British Telecom Wholesale SIP Trunk (UK)
- SIP Provider Gamma Telecom (UK)
- SIP Provider NFON (UK)
- SIP Provider Node4 (UK)
- SIP Provider TIPICALL (UK)
- SIP Provider TruSIP (UK)
- SIP Provider Virtual-Call (UK)
- SIP Provider VoiceFlex (UK)