If a phone cannot register with the system, it will typically appear offline, red, or unreachable in the portal.

Step-by-Step Troubleshooting

1. Confirm Internet and Power Connectivity

• Ensure the phone is powered on and has a solid network connection (check for physical link lights or network icon on the phone display).
• Test the LAN connection with a laptop or other device.
• If using PoE, confirm the switch or injector is delivering power correctly.

2. Check for Local Network Issues

• Ensure the phone is receiving a valid IP address from DHCP.
• Make sure the local firewall/router allows: UDP ports 5060 (SIP signalling)
• RTP range (e.g., 10000–20000) for audio.
• Disable SIP ALG or SPI Firewall if enabled on the router.
• If any malfunction causes network failure, phones will fail to register. This includes failures in routing, network infrastructure, power, internet or WAN connectivity, or cloud connectivity.

3. Confirm Provisioning and Configuration

Log in to the Portal and locate the device under Inventory > Phone Hardware.

Confirm:

• The MAC address matches the physical device.
• The correct extension is assigned to the phone. The device must have a valid user extension added to it.
• The phone is pointing to the correct provisioning URL or SIP server (typically. sip.domain.com).

4. Reboot and Reset the Device

• Power cycle the phone.
• If the issue persists, factory reset the device and re-provision using the correct template or provisioning method.

5. Check for SIP Registration 

If the phone was registered, use the SIP Flow tool to:

Look for 4xx or 5xx SIP error codes such as:

• 403 Forbidden – Incorrect password or authentication failure.
• 404 Not Found – Wrong username or extension not assigned.
• 408 Request Timeout – Registration is not reaching the server.

SIP Flow and Link: In the portal, navigate to Call History and filter the results to find calls related to the offline phone.

The SIP Flow screen opens. Click the "Share" button to copy the link to your clipboard. If you escalate the issue, retain this link and share it with the support team.

6. Validate Credentials

If the phone is manually configured:

• Double-check the SIP username (usually the extension number).
• Confirm the SIP password (available in the portal under the extension settings).
• Ensure the registration server/domain matches the one provided in the provisioning documentation.

7. Look for MAC Address Conflicts

• Ensure no duplicate MAC addresses exist in the system.
• Only one device should be assigned per MAC.

8. Firmware Compatibility

• Confirm the phone is running compatible firmware.
• Update to the recommended firmware for your model if needed.

Escalation Criteria

If all steps above have been followed and the device still won't register, escalate to support with:

• Phone make, model, and MAC address
• Device IP and network details
• Screenshot of current config
• SIP Flow links, if any, are available.