Surveillance of IP telephony may be performed through the use of
conventional telephone equipment, according to principles of the
invention while preventing giving indication to the monitored phone by
alerting the user of the monitoring phone to such surveillance use prior
to pick up by an agent for engagement of the monitoring phone in response
to the alert. Such alerts may assume many forms such as ringing, visual
indicators, data readouts, activating ancillary equipment, various flags,
etc. This alert prior to surveillance is distinct from alerts used for
normal non-surveillance calls, which the monitoring phone is capable of
receiving.