How to forward BT, Vonage and RingCentral to a LucroVox AI agent

6 min read · LucroVox UK · Updated May 2026

If you’re moving to an AI receptionist, you don’t replace your number — you keep it and forward selected calls. This guide covers the exact setup on the four UK provider types most of our customers run on: BT, Vonage, RingCentral, and a standard mobile (EE / Vodafone / O2 / Three).

Step zero: pick your forwarding mode

Before you touch any settings, decide which calls go to the AI. Most UK businesses use one of three modes:

• No-answer forwarding — rings your team first; forwards if nobody picks up after, say, 6 rings. Good if your team usually answers in hours and you want overflow cover.
• Busy forwarding — if your line is engaged, the second caller goes to the AI. Good if you’re a single-line operator who often misses second callers during a conversation.
• Always forwarding — every call goes straight to the AI. Used by businesses where the AI is the front-line front desk.

Most of our customers start with busy + no-answer — which catches the two scenarios where calls get missed without changing how things work for callers when you’re available.

BT (Business or Residential)

BT calls these Call Diversion. Most BT lines support it; some older Featureline plans require an upgrade. The codes you’ll need from the line itself:

• Divert all calls: dial *21*[number]# — replace [number] with the LucroVox UK number we’ll give you.
• Cancel divert all: dial #21#.
• Divert when busy: dial *67*[number]#.
• Cancel divert when busy: dial #67#.
• Divert when not answered: dial *61*[number]#.
• Cancel divert when not answered: dial #61#.

For BT Business Hub or BT Cloud Voice users, you can usually do all this from the admin portal instead of dialling codes — look for “Call Diversion” under your number’s settings.

Vonage Business Communications

Vonage runs entirely from its admin portal:

1. Sign in to admin.vonage.com.
2. Go to Phone System → Extensions and pick the extension to forward.
3. Open Forwarding.
4. Add a forwarding rule: If not answered after 6 seconds, forward to [LucroVox UK number].
5. Save and test by ringing yourself from a mobile.

Vonage also supports time-of-day rules — e.g., always forward after 6pm. Worth using if you want AI to handle every out-of-hours call automatically.

RingCentral / RingCentral UK

RingCentral has perhaps the most flexible UK forwarding setup. From the admin portal:

1. Phone System → Users → pick the user.
2. Phone Numbers → Call Forwarding and Voicemail.
3. Add the LucroVox number as the final destination after your team’s rings.
4. Use Advanced Rules if you want to forward only after-hours, only when unreachable, or only specific caller IDs.

UK mobile networks (EE, Vodafone, O2, Three)

All four UK MNOs support GSM forwarding codes from the handset. They’re universal:

• Forward all: **21*[number]# then press call.
• Cancel forward all: ##21#.
• Forward when busy: **67*[number]#.
• Forward when no-answer: **61*[number]#.
• Forward when not reachable (no signal): **62*[number]#.
• Cancel all conditional: ##002#.

Most carriers will charge a small per-minute rate for forwarded mobile calls — check your tariff. This is usually pennies per minute and dwarfed by the revenue you recover from missed calls.

Testing your setup (5 minutes)

1. From a different phone, ring your business number.
2. Don’t answer.
3. After your usual ring count, the call should bounce to the LucroVox UK demo agent.
4. Confirm the UK transcription notice plays and the agent handles a sample request.
5. Hang up. The agent will SMS or email you a summary, depending on how we’ve configured your account.

Common mistakes

• Setting always-forward when you meant no-answer. Easy to do with the **21*** code. Always test by ringing your line first.
• Forwarding to a UK 0845 / 0870 number that the agent isn’t set up to receive on. LucroVox UK numbers are 020 / 03xx geographic numbers; we don’t use revenue-share ranges.
• Forgetting to extend your ring count. If your phone forwards after only 2 rings, callers who would have answered get bounced unnecessarily. Six rings (~25 seconds) is a sensible default.

If you get stuck

Email support@lucrovox.com with your provider name and we’ll walk you through it. We’ve set up forwarding on dozens of UK businesses and there are very few configurations we haven’t seen.