Edit the bootserver for an Aastra phone

If your phone loses registration and cannot make or receive calls, it's possible that the phone has simply lost it's configuration files (this can happen if phones are powered off for long periods of time - the information stored within the phone's NVRAM will eventually become blank).  Think of the phone like a device which requires a little bit of power at all times.  If the "batteries die" - the information is wiped out.

Thankfully - it's extremely simple to re-register the phone with your server.