I have a (working) SIP account configured, and when not in use (ie not calling), it keeps getting disconnected after some time, showing status as 'authentication failed'.

At first I blamed the provider, but I tried three of them and it always happens.

I also set keep-alive to every possible combination, with no result.

Does anybody know what is going on and how to prevent this? In this state, I'm unable to receive VOIP calls.

Note: using power-kernel v47 and CSSU