What is SIP?
SIP stands for “Session Initiation Protocol,” which is the technology used for establishing a voice communication session on a data network. From voice calls to multi-person conference calls, SIP is the baseline technology needed to connect your voice communication back to the internet.
SIP Trunks explained
SIP is the technology, and an SIP trunk is the virtual equipment. An SIP trunk acts as an analog phone line, only virtual. These virtual lines use your data circuit (T1 line, cable modem, etc.) and connect your phone system back to the corresponding network – allowing you to access the correct IP network and engage in voice communication via internet connection.