The SIP One-Way Audio Disaster: Why NAT Traversal Leaks and Router SIP ALGs Silently Mute Enterprise Calls

calricon / field note

Few support tickets infuriate enterprise customers more than one-way audio: one party hears crystal-clear voice, while the other hears dead silence. The culprit is the architectural chasm between SIP signaling and RTP media across Network Address Translation (NAT) boundaries. From un-routable private IP leaks in SDP headers to destructive router SIP ALGs, here is why audio streams vanish and how elite telecom engineers enforce deterministic two-way voice.