Refused with code 401?

Hey

I have some Snom 320 phones as randomly lose the registration. In the asterisk server I get the following error code.

[2]20/5/2008 15:14:26: Registrar 315@XX.XX.XX.XX refused with code 401
[5]20/5/2008 15:14:26: Will try to reregister in 300 seconds

Anyone know what this code means and what the problem can be?

401 is a client error and means “unauthorized”.

Cheers.

Marco Bruni