The causes of one-way audio vary, but they usually involve issues with RTP (Real-time Transport Protocol) traffic. While SIP handles call setup, RTP carries the actual voice—and if RTP is blocked or misrouted, one party hears silence. Common culprits include firewalls that allow SIP but not RTP, NAT devices that alter IP addresses improperly, or mismatched audio codecs. It can also stem from asymmetric routing, where the return path for audio is broken. Diagnosing the issue often involves packet captures and checking the IPs and ports negotiated in the SIP headers. In hosted VoIP environments, SBCs (Session Border Controllers) are often deployed to mediate and normalize RTP traffic between networks. For businesses, persistent one-way audio leads to frustration, lost communication, and a perception of unreliability. A properly designed and tested VoIP infrastructure should account for and prevent these scenarios through NAT-aware routing, firewall configuration, and codec standardization.
What is One-Way Audio?
One-way audio is a VoIP issue where one party can hear the other, but not vice versa. It’s a common symptom of misconfigured network settings or NAT problems.
