Diagnose and fix common SIP trunk issues including registration failures, one-way audio, and dropped calls.
Trunk Shows "Unregistered"
Verify your username and password are copied exactly from the VoIPCloud portal (no extra spaces). Confirm UDP port 5060 is not blocked by your firewall. Check that SIP ALG is disabled on your router/firewall — SIP ALG corrupts registration packets on most consumer devices.
Inbound Calls Not Arriving
Log in to the VoIPCloud portal and check Phone Numbers → Assigned Numbers. Confirm the DID is assigned to your trunk. Check your PBX inbound routing rules match the DID format sent by VoIPCloud (usually local format, e.g., 08xxxxxxxx).
Outbound Calls Get Fast Busy
A fast busy (congestion) on outbound usually means the CLI is being rejected. Verify the outbound caller ID in your PBX matches an assigned DID in the VoIPCloud portal. Check your call spend controls in the portal — the account may have exceeded its daily or per-call limit.
One-Way Audio on Calls
One-way audio is a NAT/firewall issue. Ensure UDP ports 10000–20000 (RTP) are open bidirectionally. In your PBX, configure the External IP (public IP of your router) and Local Network (LAN subnet) so the PBX uses the correct IP in SDP offers. Disable SIP ALG on your router.
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