The Realtime Transport Protocol (RTP) is a common media layer shared between H.323, SIP, and Skinny (SCCP) VoIP deployments. RTP is responsible for the actual voice/audio stream in VoIP networks; hence attacks against RTP are valid against the bulk VoIP installations in enterprise environments. Since signaling (H.323/SIP/SCCP) and media transfer (RTP) are handled by two separate protocols, injecting audio into a stream is often the most damaging attack against RTP. RTP is vulnerable to audio injection due to its lack of integrity protection and its wide tolerance of sequence information.