
Concealment Techniques 䡲 99
e RTP protocol is used to carry the actual audio stream of the voice conversation, which can-
not take place until the call has been setup via SIP. You can think of RTP as the letter inside an
envelope. It contains the actual message being delivered but could not get where it is going without
the envelope.
Because these calls are using IP packets to transmit the voice stream, IP packet capturing
software can be used to listen to them. is is a three-step process that involves capturing the
packets, reassembling them into a stream, and then playing them back with an audio player
capable of handling RTP strea