Why can't faxes be sent to my local network?

Fax documents can only be sent internally and to other local networks. If a fax is to be sent externally to the same local network, this is not possible without further ado.
An alternative outside line access code is used instead of the 0 for outside line access.

Open the administration interface of the XPhone server and edit the parameter 'LocalAccess' under UM -> GATEWAY in ADVANCED SETTINGS. Enter the outside line access configured for XCAPI in the PBX system. If the 'LocalAccess' parameter does not yet exist, create it again. Example: