FortiVoice delivers integrated calling, conferencing, chat and fax.
This article explains how to set and use the twinning featureon the Fortivoice Enterprise (E) series.

The twinning feature allows a user to program their extension so that incoming calls on their desk phone will simultaneously ring on another phone number, typically a mobile or PSTN number.

There is a programmable phone key to activate or deactivate the twinning feature from a desk phone.

Pullback allows users to seamlessly continue an active twinned call that has been answered on the twinning target phone using their desk phone

FortiVoice Enterprise (E) series.  Build 293.

On the extension edit the Privilege level and check to enable twinning.

If a key is programmed on the phone, a twinning quick key can now be chosen as a programmable key.

To set the number, select Edit Preference in the extension settings, and scroll down to the twinning setting.

Activate it and fill in the phone number to dial or set this with a schedule.

Pressing the programmed key will enable or disable the feature.

Pressing this key while on a call to the cell phone, will send the call back to the desk phone to be answered there.

If the key was not enabled on the phone, dialing *73 can be used.

In this way a call can be answered on a mobile device and then switched back to a desk handset at anytime.