Malicious Caller Identification

Malicious Caller Identification (MCI), also called Malicious Call Trace (MCT) or Caller Activated Malicious Call Trace (CAMCT) is a facility which enables a phone call recipient to mark a phone call as malicious (i.e. harassing, threatening, obscene, etc.) The phone system will then automatically trace the call. The call trace is made so it will work even if the call was made from a silent number, payphone or a number with caller identification disabled; but the trace is only available to law enforcement. Generally, law enforcement will only act on the trace once a formal police report is filed in regards to the call.

How the user activates this feature depends on their phone system -- generally it is either a DTMF sequence or a special button on their phone. For analogue services, many exchanges will interpret DTMF sequences to activate POTS. Digital services, such as ISDN or GSM, enable the CPE to activate MCI via out-of-band signaling. Often with PABXs with analogue phone connections, the PABX will interpret the DTMF and then activate the out-of-band signaling.

MCI is the ETSI standard, whereas MCT is the American one. They both do more or less the same thing though.

In Canada, the service is usually marketed as Call Trace, and fees generally only apply when the service is used.