SIP Provider: A Session Initiation Protocol (SIP) connection could be a Voip (Voice over internet protocol) service furnished by many Internet telephony service companies (ITSPs) that connects a company’s private branch exchange (PBX) telephone system to the public switched telephone network (PSTN) online.Using a SIP connection may simplify administration on your organization since the SIP connection typically uses the same Internet access that’s ideal for data. This frequently removes the desire to install Fundamental Rate Interface (BRI) or Primary Rate Interface (PRI) telephone circuits.