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RTC session failure and ICE timeout — causes and troubleshooting

What RTC session failures and ICE timeouts mean in Operata, why they happen, and step-by-step guidance for identifying and resolving them.

Written by Andy Scott

What is an RTC session failure?

An RTC (Real-Time Communication) session failure means the Amazon Connect softphone was unable to establish or maintain a peer-to-peer audio connection. The most common form is an ICE Timeout.

What is ICE?

ICE (Interactive Connectivity Establishment) is the process WebRTC uses to find the best network path between the agent's browser and the Amazon Connect media servers. It works by testing different network routes — direct, via STUN, or via TURN relay — to find one that works.

An ICE Timeout means the softphone tried all possible routes and none succeeded within the timeout window. The result is a call that appears connected but has no audio.

Common causes

  • Firewall blocking UDP traffic — Amazon Connect uses UDP for media. Firewalls that block outbound UDP will prevent ICE from succeeding.

  • STUN server unreachable — STUN is used to discover the agent's public IP. If the STUN server (usually stun.amazonaws.com) is blocked, ICE candidates can't be gathered.

  • TURN relay blocked — when direct and STUN routes fail, WebRTC falls back to a TURN relay. If TURN is also blocked, ICE fails completely.

  • VPN blocking UDP — some VPN configurations block all UDP traffic or route it inefficiently, causing ICE to time out.

  • Symmetric NAT — some corporate NAT configurations are too strict for direct WebRTC connections and require TURN relay to work.

How to identify RTC/ICE failures in Operata

  1. Go to Calls and Logs and open the affected call.

  2. Look for softphone log entries containing ICE_TIMEOUT, SESSION_FAILED, RtcPeerConnectionManager SESSION Failed, or Timeout handshaking with signaling server.

  3. Note the time of the failure and the agent's network details (ISP, connection type, VPN status).

Resolving ICE timeout issues

  1. Review the Which URLs and protocols will I need to allow article and confirm all required ports and domains are allowlisted for the affected agents.

  2. Ensure outbound UDP port 443 and ports 3478/3479 (STUN/TURN) are not blocked by the corporate firewall.

  3. Configure VPN split tunnelling to allow voice traffic to bypass the VPN.

  4. If the issue persists, contact Operata support with the softphone log file from the affected call.

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