What's Happening

If an extension has gone completely silent, meaning no incoming calls are ringing through and outgoing calls are failing, the extension has likely lost registration with the Hosted PBX. This guide walks you through the four key checks to quickly isolate and resolve the issue.

Step 1: Confirm Registration Status

Log in to the Hosted PBX portal and navigate to the extension in question. Inventory > Phone Hardware

• Check the registration status indicator. A red X or "unregistered" status confirms the extension is not communicating with the server.

Step 2: Validate SIP Authentication Credentials

A mismatch in credentials is one of the most common causes of registration failure.

On the device or UC Advanced Softphone client, confirm that the following matches exactly what is shown in the Hosted PBX portal:

• SIP username (extension number)
• SIP password (authentication password, not the portal login password)
• SIP domain or proxy address

Even a single incorrect character will prevent registration. Reset the SIP password in the portal and re-enter it on the device if you are unsure.

Step 3: Run a SIP Trace Export

If the credentials look correct and the extension still will not register, a SIP trace will show exactly where the handshake breaks down.

1. In the Hosted PBX portal, go to the diagnostics or reporting section. 
2. Filter by the affected extension and set the time window to the last 30 to 60 minutes. 
3. Export the trace log and look for 401 (unauthorized), 403 (forbidden), or 408 (timeout) response codes.

Share the exported trace with support if the error code is unclear.

Step 4: Check Firewall and Network Access

If the trace shows timeouts or no response at all, the device may be blocked at the network level.

Verify the following with your network administrator:

• UDP port 5060 (SIP) is open outbound
• The RTP media port range (typically 10000 to 20000) is not blocked
• The device's IP address has not been flagged or rate-limited by the firewall

For remote or home office setups, also confirm the internet connection itself is stable and that a VPN is not interfering with SIP traffic.

What to Expect Next

Once registration is restored, place a test call in both directions to confirm audio is clear. If the extension re-registers but drops again within a few hours, escalate to support and attach the most recent SIP trace.