Troubleshooting your Trunk Groups

This guide provides best practices to resolve common trunk group issues. If calls fail, quality drops, or registration won’t stay active, it always helps to start with the basics.

Before You Start

• Identify which trunk is handling the failing call.
• Verify whether the issue is outbound, inbound, or both.
• Collect 1–2 recent example calls, including time and calling/called numbers.

30-Second Quick Checks

1. Go to My Voice Network > Trunk Groups and open the correct trunk.
2. Verify Auth Type (IP vs. SIP).
3. Ensure a Rate Deck is selected.
4. Confirm International Termination is turned On if calling abroad.
5. Check that Channels are not set too low for peak traffic. > Note: Channel costs may vary by plan. Confirm pricing or limits with your account manager if unsure.

Outbound Call Issues

• 403/401 or “No Route” Errors – Recheck SIP credentials (SIP auth) or endpoint IP/port/protocol (IP auth).
• International calls failing – Confirm International Termination is enabled.
• Busy/blocked at peak times – Increase Channels after verifying limits and pricing.
• Wrong number format – Use E.164 format (e.g., +1… for US numbers).

Inbound Call Issues

• Verify the DID is assigned to the correct trunk.
• For IP Authentication – Confirm your PBX is reachable on the listed IP/port.
• For SIP Authentication – Check that the PBX is registered and not timing out.

Audio Issues (No Audio or One-Way Audio)

• Ensure your PBX firewall allows RTP media ports.
• Disable SIP ALG on the router.
• If using TLS/SRTP, verify PBX support for the required protocol and ciphers.
• If permitted, try switching endpoint protocol between UDP and TCP.

Random Drops or Poor Quality

• Check your network for packet loss or jitter.
• Sync PBX time with NTP (time drift may affect TLS or registration).
• If multiple endpoints are configured, confirm priority/failover works as expected.

Helpful Tests

• Place a test call in both directions after each change.
• For SIP authentication, re-register the trunk after updating credentials.
• For IP authentication, add the new PBX IP as an endpoint before removing the old one.

What’s Next

• Review Create a New Trunk Group if you need a clean rebuild.
• See Edit an Existing Trunk Group to adjust endpoints, channels, or authentication settings.

Need Help?

If problems persist, contact support@trunking.io. Include:

• Example call times
• Calling and called numbers
• The trunk group name
• Whether the issue is inbound, outbound, or both