A server system exchanges trust signaling with a first access network, establishes hardware trust with the first access network, and determines that the first access network has established hardware trust with a communication interface to a second access network. The server system exchanges Session Initiation Protocol (SIP) signaling with a SIP system, establishes hardware trust with the SIP system, and determines that the SIP system has established hardware trust with the second access network and a second communication device. The server system exchanges SIP signaling with a first communication device and establishes hardware trust with the first communication device. The server system receives a SIP Invite requesting a communication session between the first communication device and the second communication device over hardware-trusted systems, and based on the established hardware trust, the server system responsively forwards the SIP Invite to the SIP system for delivery to the second communication device.