Abstract: A secure voice over internet protocol (VoIP) terminal includes a modular security manager for use in conjunction with a protocol stack thereof, wherein the security manager includes a plurality of interfaces to the stack. In an SIP embodiment, these may include a security stack interface (SSA) between an SIP manager of an SIP stack and the security manager, a security terminal interface (SST) between a telephony application and the security manager, a security media interface (SSM) between the security manager and a media controller, and a security manager application interface (SMA) between the security manager and a security application (PGP) outside the stack.