asterisk users - May 2005 - Wrong password on authentication for Notify

I have this warning popping up on one particular server.

chan_sip.c handle_response: Forbidden - Wrong password on
authentication for Notify.

I have looked around but cannot find what would be the cause of the warning?

Can anyone throw some light on this warning, why it is caused?

Thanks.

Hi,

I am trying to get to the bottom of a warning i am recieving through
the console.

May 18 13:26:29 WARNING[8281]: chan_sip.c:6837 handle_response:
Forbidden - wrong password on authentication for NOTIFY

Calls are still working. I cannot work out what is causing it.

Asterisk -> Ingate <- Asterisk.

I have googled and cannot find anything on the above.

Thanks.