This is a Voice over Internet Protocol (VoIP) and streaming media service based on the Session Initiation Protocol (SIP) by which Internet telephony service providers (ITSPs) deliver telephone services and unified communications to customers equipped with SIP-based private branch exchange (IP-PBX) and Unified Communications facilities
NumberGroup provides business quality VoIP services to wholesale operators and SIP Trunk customers worldwide. We have over 1,000,000 UK and Internaiton telephone numbers are are a license UK operator with direct PSTN connectivity.