Usually, no. On a standard UK geographic number, the person calling pays for the call, and you don’t pay a per-minute fee to receive it. But “usually” is doing a lot of work in that sentence, and plenty of businesses discover exceptions only when the first bill arrives.

This matters now because many firms are comparing quotes for the first time in years. The UK’s legacy phone network is due to be retired on 31 January 2027, and Openreach has said it will not be delayed again. Businesses replacing ISDN are reading SIP trunk quotes that look very different from the line rental bills they’re used to.

This guide explains where inbound calls cost nothing, where they don’t and what to ask before you sign.

The Short Answer

For a normal 01, 02 or 03 number, inbound calls themselves are generally not charged per minute by a SIP trunking service. What you pay for is the capacity to receive them: channels, numbers and any extras attached to your account.

That distinction is the key. You may not pay for each inbound call, but receiving calls still consumes a channel, still needs a number and can still trigger costs elsewhere.

What You Actually Pay For When Calls Come In

Channels

A channel is one simultaneous call, and it doesn’t matter whether that call is coming in or going out. If you have ten channels and ten callers ring at once, the eleventh hears a busy tone. So inbound traffic affects how many channels you need, even if it adds no per-minute cost.

Numbers

Each number has a cost, usually a monthly fee per number or per block of direct dial-in (DDI) numbers. If you keep dozens of old numbers, that fee can outweigh the channel rental. A migration is a good time to drop numbers you no longer need.

Porting

Moving existing numbers to a new provider can carry a one-off charge. Ask about the cost and the timescale, and what it would cost to move them away later.

When Inbound Calls Can Cost You Money

Freephone Numbers (0800 and 0808)

Here the cost model reverses. Under Ofcom’s rules, calls to 0800 and 0808 numbers are free for consumers from all phones, including mobiles. That doesn’t mean they’re free for the business. The organisation receiving the call generally pays, so a freephone number can be one of your largest inbound costs.

The charge can also vary by who is calling. One industry guide notes that, for 080 numbers, the charge depends on whether callers use landlines or mobiles, rather than on where you route the number. Providers often publish separate inbound rates for each, so a freephone number that suits a customer-service line with mostly mobile callers may cost more than expected.

Other Non-Geographic Numbers (084, 087, 09)

For these ranges, Ofcom’s rules split the cost of a call into an access charge that goes to the caller’s phone company, plus a service charge set by the organisation being called. If you use one of these numbers, you decide the service charge, and your provider may pay or share revenue depending on your arrangement. That’s a different commercial model from an ordinary number, so read the terms closely.

03 Numbers

These are the straightforward ones. Calls to 03 numbers cost no more than calls to geographic 01 and 02 numbers. Many organisations that once used 084 and 087 numbers have moved to 03 for that reason. Inbound handling is usually priced like a geographic number, but confirm it in your quote.

Numbers From Other Countries

If you hold local numbers abroad or international freephone numbers so overseas customers can reach you without paying, inbound calls on them are often charged per minute to you. Rates vary by country and can be high.

The Hidden Charge: Forwarded Calls

This is the most common surprise.

When an inbound call is forwarded to a mobile, the caller is on one leg and the mobile is on another. You’re often billed for the second leg as an outbound call, at your provider’s mobile rate. It also uses two channels for as long as the call lasts.

Several everyday features do this without you thinking about it:

Call forwarding to a mobile when the office is closed
Ring groups that dial external mobiles at the same time
Diversion to a backup number during an outage
Hunt groups that cascade to an outside line

A firm that diverts most calls to staff mobiles can find its “free” inbound calls producing a significant outbound bill. Ask providers how forwarded legs are billed, and whether any bundle covers them.

Extras That Can Appear on the Bill

Even when inbound calls are free, some related services aren’t:

Call recording, often charged per user or per hour of storage
Voicemail transcription or voicemail to email
Call reporting and analytics
Additional channels during busy periods
Number presentation or caller ID features
Failover or backup routing

Add any you need to your comparison, because they’re sometimes included and sometimes priced separately.

“Unlimited Inbound” and Fair Use

Some quotes advertise unlimited inbound calls. This is usually reasonable on geographic numbers, but read the definition. Check whether it excludes non-geographic numbers, whether there’s a fair-use cap and whether very high inbound volumes, such as a busy contact centre, trigger different terms.

If your business takes large volumes of inbound calls, ask whether your usage pattern would be treated as normal or exceptional.

Reading the Quote

You’ll see plenty of lists of the best UK VoIP providers online, and plenty of searches for the cheapest UK VoIP providers. Neither says anything about how a particular provider bills inbound calls on non-geographic numbers or forwarded legs. A low channel price can sit alongside expensive treatment of freephone inbound minutes or mobile forwarding.

When you compare SIP trunk providers in the UK, give each the same brief: your numbers, your number types, your approximate inbound volume and how much you forward to mobiles. Then ask for a worked example of the monthly bill.

Questions to Ask Any SIP Provider

Are inbound calls on geographic and 03 numbers charged per minute?
How are inbound calls on 0800, 0808 and 08 numbers charged, and does the rate depend on whether callers are on mobiles or landlines?
How are forwarded and diverted calls billed?
Do ring groups that call mobiles count as outbound?
What does “unlimited” exclude, and is there a fair-use cap?
Are there charges for number rental, porting or extra channels?
Which extras, such as recording, cost more?
Can you show a worked example based on our actual call patterns?

A Realistic Example

A 20-person recruitment firm in Leeds is comparing two business SIP trunking quotes. Both say inbound calls are included.

Provider A’s quote looks cheaper, but its inbound included allowance doesn’t cover forwarded legs to mobile numbers. Consultants spend much of their day out of the office, and calls ring through to their mobiles. Provider B costs slightly more per channel but includes a bundle that covers mobile forwarding.

Once the firm applies its real pattern, with most inbound calls rolling through to mobiles, Provider B comes out cheaper over a year. Without asking the forwarding question, they would have chosen A.

A Simple Checklist

List your number types: geographic, 03, freephone, others
Estimate your inbound volume, and who calls you from landlines versus mobiles
Work out how much you forward to mobiles, and when
Ask each provider to bill a worked example of your pattern
Check what “unlimited” excludes
Add recording and other extras you need
Get the answers in writing

Wavetel Business is one example of a UK provider you might speak to when comparing, and any provider offering a SIP trunk service should be willing to explain in writing how inbound, forwarded and non-geographic calls are billed. Check current rates directly with each provider, because tariffs change.

Frequently Asked Questions

Are inbound calls free on a SIP trunk?

Usually on standard UK geographic and 03 numbers, yes: the caller pays and you aren’t charged per minute. You still pay for channels and numbers, and some number types and features add costs.

Do I pay for inbound calls to a freephone number?

Typically yes. Freephone numbers are free for callers, so the organisation receiving the call generally bears the cost. Rates may vary depending on whether callers use landlines or mobiles.

Why am I being charged when calls are coming in?

Often because inbound calls are being forwarded to mobiles or external numbers, which is billed as an outbound call. Number type, extras and exceeded bundles can also be causes.

Do inbound calls use up my channels?

Yes. A channel is one simultaneous call in either direction, so busy inbound periods can affect how many channels you need.

Is “unlimited inbound” really unlimited?

Not always. Check which number types are covered, whether there’s a fair-use cap and whether forwarded legs are included.

Conclusion

For most businesses, inbound calls on standard numbers cost nothing per minute, but the picture changes with freephone and other non-geographic numbers, forwarded calls and add-on features. The charge you don’t expect is usually the one attached to a feature or number type you didn’t think about.

The practical takeaway is to tell every provider exactly how your inbound calls behave, including number types and mobile forwarding, and ask for a worked monthly bill. Start well before January 2027, so you can compare calmly.

wavetel business

Articles by wavetel

2026

Do SIP Trunk Providers Charge for Inbound Calls?