Troubleshooting FortiGate VoIP Issues (One-Way Audio, No Ringing)
April 2, 2025Voice over IP (VoIP) systems, particularly those using the Session Initiation Protocol (SIP), can sometimes encounter issues when traversing firewalls like FortiGate. Common problems include one-way audio (where only one party can hear the other) or phones failing to ring for incoming calls. These issues often stem from the FortiGate's SIP Application Layer Gateway (ALG) or session helpers interfering with the SIP signaling or RTP (audio) streams, especially when Network Address Translation (NAT) is involved.
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