FortiVoice delivers integrated calling, conferencing, chat and fax.
Article Id 193980
An initial task that is required when starting the enterprise configuration is to set names and numbers for Caller ID's across users and departments.

The following article breaks down the different sections that you can set your caller id for the FortiVoice Enterprise systems.

To control this, you will start first with your Trunks page -> and set a Voip service profile.  The Display Name and Main number at the top of this profile will be used by the system for outgoing calls.

If you find you do want to set specific numbers and names for each user, then on this trunk page you will need to check off the Caller ID modification box for the Trunk you wish to use.

With this option checked, you can now also set your own caller id and names from specific phones.  On any extension, if you click and edit the settings, you will see every extension can have the External caller ID filled in.  This can replace the Trunk Caller ID going out above and trumps it if it is filled in and supported by the Voip provider.  For example:  Some Name<15556667788> will then be sent in the invite out from the phone extension.

The other option that will over-rule the first two Caller ID numbers settings is to edit the Outbound Dial plan.  Once you set a Dialled Number Match for example, at set of extensions starting with 2XX you can then edit the Call Handling field and create a new Caller ID Modification for this trunk.  Only calls passing through this rule would have the caller id changed, and this would take precedent over all other settings.