A fax-only MIB stores a value that is used as a counter of a timer. Upon initiating or receiving a call at an endpoint with which the fax-only MIB value is associated, a user device that provides the endpoint begins a timer based on the MIB value. During the timer period processing circuitry and/or software of the user device associated with the endpoint determines whether a tone generated/received by a call being initiated/received is a fax or modem tone. If the device determines that such a tone has been generated/received, a call corresponding to the tone is processed. If the device does not determine that a fax/modem tone has been generated/received, the call being initiated or received at the endpoint is dropped.