BT Quantum: diverting calls

BethM — Fri, 31 Jul 2026 15:17:03 GMT

The BT Quantum phone system is no longer supported by BT Business. Support ended on 30 September 2025, and we won't update this page if anything changes with the product.

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We've brought our BT Quantum diverting help together in one post. It covers diverting extension and group calls, ringing another phone when yours is busy, and diverting to external numbers.

How to divert your calls

You can divert calls meant for your extension, or for the group that normally answers incoming calls. Calls can be redirected to voicemail, another extension or an external number.

To divert extension calls, follow the steps on page 36 (Diverting calls: Extension Divert section) of the BT Quantum User Guide.
To divert the group that answers incoming calls, follow the steps on pages 39 and 40 (Diverting Calls: Group Divert section) of the same guide.

Ringing another phone when yours is busy

You can programme calls to ring on another phone when yours is busy by setting a divert on busy. The other way is a linear hunt group which you can find in our BT Quantum ring groups and hunt groups post.

Diverting an extension when busy

Using a BT 8568 systemphone or a 5320/5330 IP phone:

From the idle menu, scroll until you see Divert.
Select Divert.
Select Divert on busy.
Enter an internal number, or select the extension or group from the list, to divert your calls there when your extension is busy.

Using a BT 8528 systemphone, Q DECT telephone, Q phone or a compatible standard telephone: Dial 733 followed by the extension or group number (180 to 190), followed by #.

Diverting a group when busy

Using a BT 8568 systemphone or a 5320/5330 IP phone:

From the idle menu, scroll until you see Group Divert.
Select Group divert.
Select the group you want to divert calls for. The extension may be in more than one group. A solid box shows a group that has a divert set.
Select Divert on busy.
Enter an extension number, or select the extension or group from the list.

Using a BT 8528 systemphone, Q DECT telephone, Q phone or a compatible standard telephone: dial 793 followed by the group number (180 to 190), followed by the extension or group number, followed by #.

Diverting to an external number

By default, external diversion is restricted for all extensions. You can change this in system programming: as system administrator, follow the steps on pages 56 and 57 (Extension Diverts section) of the Administrator's Guide.

Be careful: it's possible for external divert to be misused.

Once you've programmed the system, the extension user can set up the divert using the steps above.

Diverting externally without tying up two of your lines

If you have ISDN lines, you can use BT's Digital Select Service Call Deflection to 'deflect' calls to an external number. Call Deflection is a network service and must be enabled by your network provider. Once enabled, the BT Quantum can be programmed to use it and the system's divert features then deflect calls to external numbers.

BT order details:

For ISDN2e lines, the order code for Call Deflection for Standard Access lines (P-MP) is A52603.
For System Access lines (P-P), Call Forwarding must be used. The order code is A52962. For ISDN30e lines, the code is A51045.

With PSTN lines, calls can only be diverted externally from the system using Select Services Call Divert, which is a network service.

If you've got a fault on your system, you can divert your calls yourself online.

You can find details in the BT Quantum User Guide.

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