SIP is an abbreviation for “Session Initiation Protocol.” It is an Internet protocol used to begin or end live video or voice data sessions online. SIP connections can transmit voice, video and email data from one user to another. SIP connections are commonly used by VoIP, or Voice Over Internet Protocol, services as a way of allowing people to have a telephone conversation over the Internet. Getting an SIP phone number requires obtaining an SIP address, then using that with an existing phone number.
