S 4.36 Blocking fax recipient numbers

Initiation responsibility: IT Security Officer, Supervisor

Implementation responsibility: Person in Charge of the Fax System, Fax Mail Centre

If it is necessary to prevent information or documents from being sent accidentally or intentionally by fax to undesired recipient numbers, there are currently at least three technical solutions:

Some fax machines and/or fax servers allow the blocking of sending faxes to certain fax recipient numbers (positive exclusion) or, as an alternative, blocking all fax recipient numbers except for certain selected fax recipient numbers (negative exclusion).

The same type of authorisation assignment can also be carried out in modern PBX systems provided that the fax machine is connected to the telephone network using such a system.

If a fax machine or the PBX system does not offer such a possibility, one alternative is to rent an auxiliary device from the operator of the public network in order to prevent connections from being established with certain fax numbers (positive and negative exclusion).

Review questions:

• If certain fax recipients are to be blocked: Are certain fax recipient numbers blocked on the fax machine, fax server, on the PBX system or by the network operator and/or only certain fax numbers allowed?