SIP Trunking vs Cloud Telephony

Both replace the lines that stop working in January 2027, and they are not alternatives to each other so much as answers to different questions. Which one fits depends almost entirely on the phone system you already own.

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The question is what happens to your phone system

Almost everyone arrives at this comparison for the same reason: the PSTN and ISDN network closes in January 2027, and the lines feeding their phone system go with it. The choice that follows is narrower than it looks. SIP trunking keeps your existing phone system and replaces only the lines into it. Cloud telephony replaces the phone system as well, and there is nothing left on site but handsets and a network connection.

So the honest first question is not which is better but how old your phone system is and how much life is left in it. A modern on-premise system bought in the last few years, already SIP-capable, with a maintenance contract and features your business depends on, is worth keeping — SIP trunking is cheaper than replacing it and takes an afternoon. A system that predates the smartphone, needs a specialist to change an extension, and would need replacing before 2027 anyway is not worth spending money to keep alive. That is a cloud conversation.

The second question is where your people are. SIP trunking serves a building: it feeds a system that lives in a comms cupboard, and remote workers are an add-on to it. Cloud telephony has no building at all — an extension is wherever the person is, which is why it suits a business with home workers, several sites, or staff who spend the day in vans. Neither is more modern than the other in any way that matters. They are shaped for different businesses.

How they actually differ

Where the system lives

SIP: on your premises, as it does now. Cloud: in a data centre, with nothing on site but handsets and the network.

What you spend

SIP: keeps your capital investment, lower monthly cost, no new hardware. Cloud: no capital outlay, higher per-user monthly, no maintenance contract.

Adding and removing people

SIP: limited by the licences and capacity of the system you own. Cloud: change the licence count and it takes effect the same day.

Multiple sites

SIP: each site generally needs its own system, or links between them. Cloud: sites are a detail — everyone is on one system regardless.

What happens when hardware fails

SIP: a failed on-site system is your problem and your engineer visit. Cloud: there is no on-site system to fail, and calls reroute to mobiles.

How long it takes

SIP: often an afternoon, since the system stays put. Cloud: usually longer, because handsets, routing and training all change together.

Who we work with

We are independent of any single network or vendor, so the recommendation follows the requirement.

Telephony platforms

Hosted, on-premise or Microsoft Teams — the right answer depends on the building, not on what we prefer to sell.

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Which one is probably right for you

Your phone system is under about five years old, SIP-capable and doing its job — SIP trunking, almost certainly
Your phone system is older than that, or nobody left knows how to configure it — cloud, and stop paying to maintain it
Everyone works in one building and always will — SIP is the cheaper answer and there is no shame in it
You have home workers, several sites, or people who work out of vehicles — cloud, comfortably
You are moving premises in the next couple of years — cloud, so the move is a change of address rather than a project
You have a contact centre or heavy call routing on the existing system — get it looked at properly before deciding either way

SIP Trunking vs Cloud Telephony — Common Questions

Is cloud telephony always better than SIP trunking?

No, and anyone saying otherwise is selling. If you own a modern phone system that works, SIP trunking keeps it and costs less every month than replacing it. Cloud wins where the system is old, where people are spread across sites or homes, or where nobody wants to own hardware again — which is a lot of businesses, but not all of them.

Which is cheaper?

SIP trunking is usually cheaper monthly, because you are only paying for lines and you already own the system. Cloud costs more per user per month but has no capital outlay, no maintenance contract and no replacement bill in five years. The honest comparison is over the life of the system rather than the first invoice.

Do both of them solve the 2027 switch-off?

Yes. Both move you off the copper network that closes in January 2027, which is the part that is not optional. That is worth being clear about because the deadline is often used to push a full cloud migration when SIP trunking would have met it perfectly well and cost less.

Can I start with SIP trunking and move to cloud later?

Yes, and it is a sensible path when a phone system has a few years left. SIP now buys time and meets the deadline; cloud follows when the hardware genuinely reaches the end of its life. Your numbers carry through both moves, so nothing on your signage changes either time.

What if my phone system is not SIP-capable?

Then SIP trunking needs a gateway to translate between the system and the network, which adds cost and a piece of hardware to a system already near the end of its life. At that point the arithmetic usually favours cloud. It is worth checking rather than assuming — some older systems take a licence rather than a box.

How do I find out what phone system I actually have?

The make is usually printed on the handsets, and the model on the cabinet wherever the lines come in. If neither is obvious, send a photo of a handset and of the cabinet and we can identify it. It is the first thing we ask, because the answer decides most of this comparison for you.

Not sure which side you fall on?

It usually takes ten minutes to work out, and it comes down to what you already own. Tell us the make and rough age of your phone system and where your people work, and we will tell you which one fits — including when the answer is to keep what you have.

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