How CallerID Works

CallerID is a service offered by most telephone companies to provide the identification of who is calling.  In the US most telephone companies offer CallerID service, usually as a low cost add-on option to your telephone service, that provides the telephone number of each caller.  Many US firms also offer expanded CallerID service that includes both the number and caller name information as part of CallerID.

In the US and Canada, CallerID information occurs as a short data stream between the first and second telephone rings for an incoming call.  CallerID data is actually sent via audible tones that can be heard by simple recording equipment.  The fact that standard CallerID is audible tone based is one of the reasons that the data is not always accurate.  Any noise that occurs on the line during that short period after the end of the first ring can disrupt or otherwise make the detection of the CallerID signal difficult.

CallerID is handled somewhat differently in other countries.  In the UK, the data occurs before the first ring.  In some other countries a different approach is used that is not audible tone based.

All versions of CallAudit software include support for CallerID processing.  The issue for most users is whether they have a device installed that can provide CallerID data to their PC and CallAudit.  See the Modem section for more information about modem use with CallAudit and support for CallerID.