PRI vs SIP Trunking

The Difference between PRI (Primary Rate Interface)
and SIP (Session Initiating Protocol)

Why does it matter to your business?

PRI and SIP Trunking are two different methods to connect your business to a regional telephone network.

Both methods require PBX (Private Branch Exchange) equipment where the interchange between your office or facility and public lines takes place. Most existing PBX and IP PBX equipment can support both PRI and SIP Trunking connections, either directly or with an adapter. This makes either an affordable option for most businesses. So what’s the difference?

When making a decision for your business, the number of users, concurrent phone calls, and scalability to match future needs are all important considerations.

PRI vs SIP at a glance

PRI Trunking
A PRI is a single physical connection (traditionally T1) with 23 voice channels. Now, your business can elect to have up to 100 phone numbers on a single PRI, but that single PRI can only handle 23 simultaneous phone conversations. PRI is a voice-only connection dedicated to phone transmission. Where PRI may have disadvantages for optimal scalability it stands as a higher quality voice option than voice-over-IP options.
SIP Trunking
SIP enables businesses to use your existing Ethernet/fiber connection as a voice solution. Called VoIP (Voice over Internet Protocol), SIP connects your existing PBX interchange to a data network. This virtual connection uses a packet switched model to connect voice to voice, from phone to data connection to your regional phone lines.
Expanding with PRI
Because each PRI connection provides a maximum of 23 simultaneous calls, a business that demands more will need to purchase additional PRI lines to accommodate up to 46, 69, and so forth.
Expanding with SIP
Adding users to SIP Trunking is easy. Simply tell us how many users you need and each gets assigned a virtual connection and individual phone number or extension based on your needs.