asterisk users - Jan 2005 - Stanaphone incoming calls problem.

Hi,
I have an stanaphone number, and when I first start asterisk everything
works fine, but after a few hours of asterisk running incoming calls fail,
and when calling my stanaphone remotely, it takes me directly to the
stanaphone voicemail, restarting asterisk fixes the problem for a few
hours.

I believe the problem is due to the fact that I have a dynamic IP, and the
IP might be changing very often. Is there a way to force asterisk to re
register to stanaphone at some time intervals ? or some better way to fix
this problem.

Has anyone had this problem ?

Any help will be greatly apreciated.

Thanks,

Sergio Riveros