What is SIP?

SIP has opened up a greater opportunity for businesses and telecom providers alike, given the ease of setup and its low cost.

SIP stands for Session Initiation Protocol. IP telephony and communications are defined by key protocols, among these Protocols is the Session Initiation Protocol.

Session Initiation Protocol (SIP) is a powerful communication protocol for signaling and controlling multimedia communication sessions allowing people to communicate over the internet via their phones or computers. SIP trunking is the modern-day PRI or TI lines. Businesses and individuals will purchase a SIP trunk from an ITSP and connect it to their IP PBX, or have it set up by the providers themselves.

In the past, one would buy a TI trunk from a Telco provider and connect it to the legacy PBX.

These days, you do not need to route voice calls over copper lines and circuit-switched networks. SIP trunks use a packet switch network in which voice calls are broken down into digital packets and sent over data networks. This allows you to make video and voice calls, conference calls, send and receive instant messages, and distribute media.

A report from Future Marketing Insights showed North America as the largest market share currently for the Session Initiation Protocol (SIP) trunk market due to the high adoption of SIP among enterprises in the U.S. – likely as a way to reduce their monthly telecommunication expenses.


PSTN stands for Public Switched Telephone Network. This is the traditional circuit-switched telephone system that uses underground copper lines to transmit analog voice data enabling people to make calls around the world.

Unlike SIP, PSTN lines require a physical connection in different points to complete a call.

On the other hand, SIP trunking utilizes a packet switch network. In this, voice calls are broken down into digital packets and sent across network to a selected destination.

SIP works with an IP-enabled PBX (private branch exchange), while a PSTN system is made up of physical switches centralized at specific points on a particular network. The connection of the multiple switches is what enables the communication between two points on a network.

What is a SIP Phone Number?

A SIP phone number is essentially a telephone number given by an ITSP via SIP protocol.

Unlike the ordinary telephone number, which is restricted to specific geographical areas, SIP numbers can be used anywhere, and the owner can carry it everywhere, made possible by the forwarding process to a SIP destination such as an IP telephone.

Do you have any questions regarding SIP trunking and how it works? Can you consider installing it in your business? Feel free to get in touch with us!