Phones - What do I do when my phones keep changing to Unreachable over time?

If you are experiencing issues where either internal or external Digium phones become unreachable over time, the issue may be caused by ports being closed on networking equipment between the Switchvox and the phones. Many routers or firewalls that deal with NAT will close ports if there is no activity after a certain period of time. By enabling UDP Persist-Connection using the steps below, you can force the phone to periodically send a SIP Options message to Switchvox, keeping the port open:

1. Navigate to Server -> Networking -> Phone Networks

2. Select the network the phones are using and click Modify

3. Click Advanced Settings

4. Set Enable UDP Persist-Connection to Yes

5. Set UDP Persist-Connection Interval to 30

6. Click Save Phone Network

Note: This setting only affects Digium phones.