Call divert codes UK: the three settings everyone forgets

You set a call divert, tested it by letting the phone ring out, and it worked. Then a week later your phone died on a job and a caller got dead air. Nothing was broken — on UK mobile networks, "when I can't answer" is three separate settings and you only set one of them. Here are all three codes, the landline equivalents, how to check what's live and how to cancel it cleanly.

Why one code isn't enough

Mobile networks don't have a single idea of "unavailable". They have four distinct conditions, and each one has its own divert slot in the network. Set one and the other three carry on doing whatever they were doing before — usually sending the caller to your network voicemail, or to nothing at all.

The last three together are what most people mean by "forward my missed calls". They're often called conditional diverts. You need all three set to the same destination, or your cover has holes in it.

The hole that catches people out is unreachable. That's the one that fires when you're in a basement, in a loft, in a plant room, or when the battery goes at 4pm. Which is to say: exactly the moments you're least able to answer, and exactly the calls you'd most want caught.

The codes for UK mobiles

These are GSM supplementary service codes. They work on the keypad of any UK mobile — EE, O2, Vodafone, Three and the networks that run on them. Type the code into the dialler and press call. You'll get a confirmation message back from the network within a second or two.

Replace NUMBER with the full number you want calls to land on, including the leading 0.

So if your destination number were 02079460000, you'd dial three codes, one after the other:

1. *6102079460000#** then call — no reply covered.
2. *6702079460000#** then call — busy covered.
3. *6202079460000#** then call — unreachable covered.
4. Each one should return a short "Setting activation succeeded" style message. If it doesn't, see the troubleshooting section below.

Changing the ring time before it diverts

The no-reply divert has a timer, usually 15 or 20 seconds by default. You can set it yourself by adding a number of seconds to the end of the code, in multiples of five, up to 30:

*61NUMBER20# gives you 20 seconds of ringing before the call moves on.

Shorter means the caller waits less and is less likely to hang up. Longer means you get a better chance to dig the phone out of your pocket. Twenty seconds is roughly four or five rings — a sensible middle. Ten seconds is often too aggressive if you drive a lot; the phone barely starts before the call is gone.

How to check what's actually set

This is the step nobody does, and it's the one that answers "is it even on?" without ringing yourself from another phone. Dial these and the network tells you the current state of each divert:

The reply comes back as a short network message listing the service and the number it points to. If a divert is off, it'll say so — "not forwarded" or similar. Screenshot it. When something stops working in three months' time, you'll want to know what it looked like when it worked.

How to cancel a divert

Cancelling is as specific as setting. Each slot has its own cancel code:

##002# is the one to remember. It wipes every divert on the line in a single go. If you've inherited a handset, or you're switching answering providers, or you simply can't work out why calls aren't reaching you — dial it, start from a blank slate, then set the three you want.

A note on the difference between # and ##. A single hash deactivates a divert but keeps the number stored, so you can turn it back on later with 1# alone. Double hash erases it entirely. Erasing is cleaner. Half-remembered stored numbers are how people end up diverting to a provider they cancelled two years ago.

When the codes don't take

A few things get in the way, and they're all fixable.

• Diverts are barred on the account. Some business tariffs and most pay-as-you-go plans have call forwarding switched off at network level. One call to the network turns it on. Ask specifically for "conditional call forwarding" so you don't get the "all calls" setting only.
• You typed a space or a +44. Use the plain national format starting 0, no spaces, no country code. Some networks accept +44 but not all of them do it consistently.
• Dual SIM. The code applies to whichever SIM the dialler is currently set to use. If you have a work SIM and a personal SIM in one phone, check which one is selected before you dial.
• iPhone Settings vs the codes. The Settings → Phone → Call Forwarding toggle on an iPhone only controls the all calls divert. It does not touch no reply, busy or unreachable. If you've used it and wondered why conditional forwarding didn't appear, that's why — use the dial codes instead.
• Wi-Fi calling and VoLTE. On some networks these interact oddly with the unreachable divert. If the unreachable test fails and everything else passes, try toggling Wi-Fi calling off, re-dial *62NUMBER#**, and retest.

Landlines: it depends who your provider is

Traditional landline diverts use *\21\* for all calls, and you cancel with #21#**. That part is near-universal. The conditional ones are not universal at all — they're sold as separate features with different names, and on a basic residential line they often don't exist.

• Divert all calls: 21NUMBER#, cancel with #21#. Listen for the confirmation announcement.
• Divert on busy and divert on no reply are usually chargeable add-ons on an old-style BT line, and the codes vary. Ring your provider and ask which call diversion features are enabled on the line and what the codes are.
• Charges. On landlines, diverting a call normally costs you the onward leg — your line pays to connect the caller to the destination number. It's small, but it isn't zero. Check the rate before you divert a landline to a mobile.

Most UK landlines are now digital voice services running over broadband rather than copper. If yours has been switched, see the VoIP section — the dial codes may have stopped working entirely.

VoIP lines: there are no codes, there's a control panel

If your number lives on a VoIP or cloud phone service, forget the keypad. Diverts are configured in the provider's web dashboard, usually under a heading like call flow, call routing, forwarding rules or failover.

The good news is you usually get more control than the mobile codes give you, not less. A typical VoIP panel lets you set a ring time, then a sequence of destinations, then a final failover — and often different rules for business hours and out of hours. The bad news is that every provider's interface puts it somewhere different, and the terminology drifts. Look for whatever the panel calls the "no answer" or "timeout" destination and the "unavailable" or "failover" destination. They're the two that matter most.

If you're not sure what shape your phone setup actually is — mobile, landline, VoIP, virtual number, or some accumulated mix of all four — the small business phone system guide walks through each one and what it fixes.

What should the calls divert to?

The codes are only half the job. The destination matters more. Your three realistic options:

Voicemail is the default and the reason diverts feel pointless. Somebody who needs a plumber at 7pm doesn't leave a message, they ring the next name on the list. If you want the arithmetic on that, what missed calls really cost a UK trades business does the sums properly.

Where this won't help you

Diverts have real limits, and it's worth knowing them before you spend an evening on this.

• If you answer almost everything already, diverts fix nothing. One caller a fortnight hitting voicemail isn't a problem worth a monthly bill.
• If the issue is capacity, not availability — you're answering fine but you can't get to the work — a divert just moves the bottleneck. You need pricing or hiring, not routing.
• If you've rejected a call deliberately, the busy divert fires and your caller gets forwarded anyway. If you screen nuisance calls by hitting red, expect them to reach your destination. Block them properly instead.
• If your number is listed at several places — Google, a directory, an old flyer — diverting the main number only covers the main number. Any other line needs its own three codes.
• If you share a handset with a partner or family, an all-calls divert catches personal calls too. Conditional diverts are usually safer for mixed-use phones.

Where RedAgents fits

If the destination you want is an AI receptionist, the setup is the same three codes — you just point them at the number you're given rather than at voicemail. Your own number stays exactly as it is on the van, the website and the signwriting. Nothing to reprint, nothing to tell customers.

RedAgents walks you through the dialling with a wizard, which mostly means it works out which codes your network wants and hands them to you in the right order so you're not reading a table on a phone screen while standing in someone's kitchen. You can do it manually from this post if you'd rather — the codes are the codes.

Calls you answer yourself ring as normal; only the ones you can't take get forwarded. What happens after that — the greeting, what it knows, what it does out of hours — is covered in what actually happens when an AI receptionist answers, and the plans start at £29 a month with 100 call minutes included, with a 7-day free trial and 30 call minutes, no card needed. Full detail on the AI receptionist page.

A ten-minute checklist

1. Dial #002# and read what's currently set. Screenshot it.
2. Dial ##002# to clear everything out.
3. Decide your destination number and write it down with no spaces.
4. Dial *61NUMBER20# — no reply, 20-second ring.
5. Dial *67NUMBER#** — busy.
6. Dial *62NUMBER#** — unreachable.
7. Dial #002# again and check all three show the right number.
8. Ring yourself three ways: ring out, while on a call, and with the handset off.
9. If any of the three fails, ring your network and ask them to enable conditional call forwarding on the account.

Ten minutes, once. The phone keeps ringing in your pocket exactly as it always did — it just stops going quiet when you can't get to it.