How to Divert Calls on BT Business Landlines

By Tony Dalton, founder of AI Answerphone · Published · Updated

To divert every call on a BT Business landline, dial *21*, then the number you want calls to go to, then #. Use *61* instead to divert only calls you don't answer, or *67* for calls that arrive while you're on the phone. Cancel with #21#, #61# or #67#.

These codes are for a standard BT business phone line. If your business is on BT Cloud Voice or Digital Voice for Business, skip to the Cloud Voice and Digital Voice section, because those services work differently.

Before you start, check two things. Call Diversion is a paid-for feature on BT's standard lines, so it needs to be on your line. And your phone needs to be set to tone dialling: when you press * or # you should hear a musical tone, not a click. BT's own steps are on its Call Diversion help page.

1. Divert all calls

Every incoming call goes straight to the number you choose. Your desk phone won't ring at all.

*21*[number]#

To cancel: #21#

To check: *#21#

Enter the number in full, including the area code, for example *21*01632960000#.

2. Divert when you don't answer

Your phone rings first. If nobody picks up, the call diverts. BT's business help gives the ring time as 15 seconds on one page and about 20 seconds on another, so expect roughly that. BT doesn't publish a code to change it on a standard line.

*61*[number]#

To cancel: #61#

To check: *#61#

3. Divert when busy

Calls divert only when your line is already engaged. Set it alongside the "don't answer" code to cover both calls you miss and calls that arrive while you're busy.

*67*[number]#

To cancel: #67#

To check: *#67#

How you know a divert is on

BT says you'll hear an intermittent dial tone when you pick up the phone while a divert is set. One catch: if you have Call Minder, that same broken tone can also mean you have a new message. If you're not sure, dial the check code for that divert type.

BT Cloud Voice and Digital Voice for Business

On these services, the *21* style codes above aren't how BT documents it. You set call forwarding online instead.

  • BT Cloud Voice: sign in to the Business Portal, choose Users, pick the user, open Features and choose the forwarding type. The options are Always, Busy, No Answer, Not Reachable and Selective. Selective can forward calls by time of day, which suits out-of-hours cover. Cloud Voice also has handset codes: *72 turns on forward-always and *73 turns it off. See BT's Cloud Voice forwarding guide and feature access codes.
  • Digital Voice for Business: the steps are the same, in the Digital Voice for Business portal (Users, then Features, then the forwarding type). See BT's Digital Voice for Business forwarding guide.

Not sure which service you have? Your BT bill or contract names it, or BT Business can tell you.

What diverting costs

There are two parts. On a standard line, Call Diversion is a feature you pay for. On top of that, BT says the diverted part of each call is charged at its standard rates, as if you'd made that call from your line. Those charges show on your BT bill.

Your caller pays for their call to you as normal. You pay for the leg from your line to wherever you've diverted it. Check your BT tariff before you set a long-running divert.

If the divert won't work

These come from BT's Call Diversion problem-solving page:

  • You hear "service unavailable". Call Diversion probably isn't on your line. Ask BT to add it.
  • The code does nothing. Check the phone is on tone dialling. Some older handsets won't send the codes, so try another phone.
  • Call barring is on. Outgoing Call Barring blocks diversion. Dial *#34# to check whether it's active.
  • Calls still go to voicemail. BT lists 1571 and Call Minder as services that can get in the way of setting a divert. If unanswered calls keep going to your BT voicemail, raise that with BT.
  • It won't cancel. Use the cancel code that matches the divert you set: #21#, #61# or #67#.

Always test it. Ring your business number from a mobile. With an all-calls divert, it should go straight through. With a no-answer divert, let it ring and it should move on after the delay.

Diverting your BT line to AI Answerphone

When you sign up, we give you a UK number. You keep your BT number and divert it to ours. Our AI answers in a British voice, asks for the caller's name, number and what they need, then sends you a summary and transcript by email, WhatsApp or SMS.

Pick the divert that matches how you work:

  • Calls you miss: set *61* and *67* to your AI Answerphone number. Your phone still rings first, and the AI only takes calls you can't.
  • Out of hours only: dial *21* with our number when you close and #21# when you open. On Cloud Voice, a time-based Selective rule can do this for you. More on out-of-hours call answering.
  • Every call: set *21* and leave it on. The AI answers every call, day and night.

Then test it: call your BT number from another phone and let the AI take the call. The details should arrive where you've asked for them.

The AI takes messages. It doesn't book appointments or transfer calls to you, so someone from your team calls the customer back.

Common questions

Can I divert my BT landline to a mobile?

Yes. Use any of the codes above with the mobile number. You pay BT's rate for a call to that mobile for the diverted part of each call.

Can I use the no-answer and busy diverts together?

Yes. They're separate settings, so you can set *61* and *67* to the same number. Check each one afterwards with *#61# and *#67#.

Does the caller know they've been diverted?

They dial your usual number and the call is answered elsewhere. They don't need a different number.

Can I set a divert when I'm away from the office?

On a standard line, you dial the codes from a phone on that line. On Cloud Voice and Digital Voice for Business, you can change forwarding in BT's online portal.

How quickly can I start diverting to AI Answerphone?

Your AI Answerphone number is usually ready within 24 hours of signing up. Plans start at £47 a month with no contract.

Let the AI take the calls you can't

Divert your BT line once, for every call or just outside opening hours, and AI Answerphone will:

  • Answer in your business name, in a British voice.
  • Take the caller's name, number and enquiry, 24/7.
  • Send you a summary and transcript by email, WhatsApp or SMS.
See plans and prices