A method and security system arrangement are disclosed for processing incoming signals at an alarm monitoring station. The method includes analyzing the incoming signals to assess if any particular incoming signal includes characteristics of a facsimile signal to thereby identify whether or not a given incoming signal is a facsimile signal. If the analyzing identifies that a given incoming signal includes characteristics of a facsimile signal, thus identifying that the given incoming signal is likely a facsimile signal, the alarm monitoring station refrains from initiating an alarm handling procedure to handle the given incoming signal. Caller ID information may be extracted from the facsimile signals received by the alarm monitoring station, and added to a call block list. Calls originating from caller IDs on the call block list may be blocked by the alarm monitoring station.