What is a SIP Trunk?

A SIP trunk is just the modern way we make and receive phone calls, using the internet.
Think of them as phone lines, only seriously upgraded.

That’s the simple version without the telecoms jargon.

From a customer’s point of view, nothing really changes. Your phones still ring, you still make and receive calls, and your business keeps running as normal. The difference is what’s happening behind the scenes.

Traditional phone lines were quite rigid. If you needed extra lines, have moved offices, or wanted calls routed differently, it could quickly become awkward and expensive. SIP makes all of that much simpler. You can scale up more easily, route calls between sites or mobiles, and generally have far more control over how your business handles calls.

They also tend to work better with modern business phone systems, especially VoIP and hosted telephony setups.

Another reason SIP trunks have become so important is the UK PSTN switch-off. The old phone network is being phased out, which means businesses still relying on traditional ISDN or PSTN services will eventually need to move to an internet-based solution anyway.

And despite the slightly technical name, most businesses using SIP trunks don’t really notice them day to day — which is probably how it should be. Your phones just work, your calls sound clear, and the whole thing quietly runs in the background without needing much attention.

That’s usually the goal with good telecoms.

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