Device authentication challenge deadline

The pbx received a clear request (INVITE \ REGISTER) and sent only one 401 (authentication challenge) after which nothing more arrived from the remote device.

Possible causes:

1. Although quite rare, there are terminals that do not support authentication via username and password. These terminals, once they receive a negative response with a 401, do not retry authentication with the authentication credentials.

Possible solutions:

1. If supported, enable authentication on the terminal. Otherwise, contact the manufacturer of the device for an update of the device or change the type of device.