Define caller ID for outbound fax independent from the voice extension caller ID

The fax station ID (referred to as "ConnectedLineName" in the Asterisk log) can be properly set up in the fax configuration of a particular user. This causes printing the fax station ID on the top line of a fax being sent from this particular fax-enabled user. However, when a user sends a fax, e.g. by using the "send fax" functionality available at UCP or Zulu, the conventional caller ID as defined for the extension or for the trunk is used as caller ID.

This is extremely inconvenient, as the receiving fax machine believes that the provided caller ID is the caller ID of the fax recipient of the user. In fact, the provided caller ID is the conventional number used for voice connections.

It is common practice that a company's fax has a dedicated extension and therefore a dedicated caller ID. It is further common practice that the fax extension related to a particular user is prefixed by a unique id, for example, prefix 7. So if omeone wants to send a fax to a user with voice extension 50, the fax should be sent to 750. If the fax comes from external, the public number needs to be prefixed.

At present, this convenient addressing is not reflected in the fax being sent from a particular user. For example, when configuring the user with voice extension 50, I would like to define a fax extension 750.

Furthermore, I would like to prefix the trunk number to the configured extensions. We have extensions available for different trunks. So it would be more convenient to define only a caller ID extension portion which is prefixed by the trunk number actually used for an outbound call.