RTP Replay Attack
Microsoft Office Communications Server 2007 and Microsoft Office Communications Server 2007 R2 will reach end of support on January 9, 2018. To stay supported, you will need to upgrade. For more information, see Resources to help you upgrade your Office 2007 servers and clients.
A replay attack occurs when a valid media transmission between two parties is intercepted and retransmitted for malicious purposes. SRTP used in connection with a secure signaling protocol protects transmissions from replay attacks by enabling the receiver to maintain an index of already received RTP packets and compare each new packet with those already listed in the index.