What is SIP?

Everything you need to know about SIP Trunks

What is SIP?  

SIP stands for Session Initiation Protocol. It’s a technology that enables data, voice and video calls to be delivered over the Internet.

What is a SIP Trunk?  

Traditionally, businesses have relied on physical phone lines to make and receive calls. These lines are either analogue (over copper wires), or digital (using ISDN).  

A SIP trunk connects your customer’s premises directly to the PSTN (Telephone Network) via the Internet.  

It is commonly sold as a replacement to ISDN – but unlike this older technology it allows voice, data and video to be transferred over the same connection.

How do SIP Trunks work? 

Most businesses have a phone system in place – this is sometimes called a PBX (Private Branch Exchange).

The phone system allows people to communicate both with the outside world and internally with each other using phone extensions.

If the physical phone lines are removed, they still need away to connect these systems to the phone network to make and receive calls.

That’s where SIP trunks come in.

SIP connects the customer’s phone system to the phone network via the Internet. Customers can use either an existing or new broadband connection or a leased line.


Why SIP Trunks are Right for you  

ISDN is reaching the end of the line and Ofcom has directed the telecom sector to shut the service down completely in 2025.

It means any current businesses using ISDN need to start looking at alternatives sooner rather than later. If a customer has access to the Internet and wants to buy an IP-PBX, they can replace their BT ISDN with a SIP Trunk solution which could be up to 50% cheaper.

SIP is Feature Rich, easily scalable, and future proof, With collaboration that allows users to work from Anywhere.

With SIP, cost is not based on a per line or user basis, but on the number of concurrent calls you wish to be able to make. This can often, for larger teams, end up being much more cost-effective in the long term.


For more information contact us on 0191 4198181
or email info@siriustelecom.uk