How to Transfer Calls from Your Landline to a Mobile
To transfer calls from a UK landline to a mobile, pick up the handset, dial *21* followed by the full mobile number, then press #. A confirmation tone tells you it's active, and every call to that landline will now ring your mobile instead. To cancel it, dial #21#. This standard code works across BT, Sky, TalkTalk, and most other UK landline providers, since it's based on the same underlying network feature rather than anything provider-specific.
Call Diversion Codes You Can Use
There are three main diversion types, each using a different code:
| What it does | Code to set | Code to cancel |
|---|---|---|
| Divert all calls immediately | *21*[mobile number]# |
#21# |
| Divert only unanswered calls (after around 15 seconds) | *61*[mobile number]# |
#61# |
| Divert only when the line is engaged | *67*[mobile number]# |
#67# |
You can also check whether a diversion is currently active by dialling *# followed by the relevant code and # — for example, *#21# to check whether all-calls diversion is switched on.
How to Divert All Calls
- Pick up your landline handset and wait for a dial tone.
- Dial
*21*, then your full mobile number, then#. For example:*21*07700900123#. - Listen for the confirmation tone — a short, interrupted dial tone confirms it's set up correctly.
- Replace the handset. Every incoming call to that landline now rings your mobile instead.
How to Divert Only Unanswered or Engaged Calls
If you'd rather keep calls ringing on the landline first, and only fall back to your mobile when there's no answer or the line's busy, use the other two codes instead of *21*:
- Unanswered calls: dial
*61*[mobile number]# - Engaged/busy calls: dial
*67*[mobile number]#
Both work the same way as the all-calls version — dial the code, enter the mobile number, press #, and listen for the confirmation tone.
How to Check or Cancel a Diversion
To check whether a diversion is currently active, dial *# followed by the code and # — for example *#21#. To cancel any diversion, dial # followed by the code — for example #21# cancels an all-calls diversion, and #61# cancels an unanswered-calls diversion. You'll hear a confirmation tone once it's switched off.
What Does It Cost?
Diverted calls are typically charged at your provider's standard outbound calling rate to a mobile, starting from the moment the mobile begins ringing, not from when you actually answer. This can add up quickly for a business fielding a reasonable volume of calls, particularly if the diversion is left on permanently rather than used occasionally. It's worth checking your specific provider's rate before relying on this for anything more than short-term or occasional use.
A Better Long-Term Option for Businesses
Standard call diversion is a useful short-term fix — heading out for the day, or covering a temporary gap — but it's not really designed for permanent, everyday use, given the ongoing per-minute cost. For businesses wanting calls to genuinely follow them to a mobile as standard practice, a VoIP phone system with its own mobile app is usually the better long-term answer, since calls arrive directly through the app using your business number, without the same call-charge structure. Our guide to auto-diverting calls on a business mobile covers this in more detail, including setup on iOS and Android.
Frequently Asked Questions
Does this work on any UK landline, or only BT?
The *21*, *61*, and *67* codes are standard across most UK landline providers, including BT, Sky, TalkTalk, and Plusnet, since they're based on a shared underlying network feature rather than something unique to one provider.
Will the caller know their call has been diverted? No, diversion is invisible to the caller — they simply hear the phone ring and get connected as normal, with no indication the call has been forwarded elsewhere.
Can I divert calls to another landline instead of a mobile? Yes, the same codes work for diverting to any UK landline or mobile number, not just mobiles specifically.
Is there a way to divert calls without paying per-minute call charges? Standard network-based diversion is generally charged per minute. A VoIP phone system with its own mobile app avoids this cost structure, since calls are delivered through the app directly rather than as a diverted call.
If you're diverting calls to your mobile regularly rather than occasionally, it's worth looking at whether a VoIP system would work out better long-term. Request a quote for independent advice, or read our guide to setting up auto-divert on a business mobile.
