Unchecking Validate Certificates on an Aastra phone can address a Bad Certificate error. See Aastra IP Phones: Bad Certificate Error for more information.
Unchecking Validate Certificates
- Log in to the IP Phone web GUI. (On the phone itself navigate to Options > Phone Status > IP & Mac Address.)
- Open a web browser, type the IP address that was shown on the phone (e.g., 192.168.x.x).
- On the left hand menu go to Advanced Settings > Network > HTTPS Settings > uncheck the Validate Certificates.
If unchecking Validate Certificates method doesn't work:
- Login to the IP Phone web GUI. (On the phone itself navigate to Options > Phone Status > IP & Mac Address.)
- Click Reset.
- Click the button to Remove the Local Configuration. (Do not restart the phone.)
- Log in to the customer's router.
- In the router, set a static primary DNS to 126.96.36.199 and secondary DNS to 188.8.131.52.
- After that is done, go back to the phone's UI.
- Go back to Reset.
- Click the button to Restore to Factory Defaults (Do not restart the phone.)
- Click Preferences and hard code the primary Time Server to either 0.pool.ntp.org or 1.pool.ntp.org (1.pool.ntp.org is preferred).
- Save the settings.
- Restart the phone.
The problem with Bad Certificate errors is that the time on the phone does not match the HTTPS certificate coming from the server. What we are doing here is wiping whatever config was on the phone and restoring it to its initial state, then we are hard-coding the time server to get around the Bad Certificate error.