[asterisk-users] Polycoms lose registration and won't re-register

[ewr at erols.com]

I have made a little progress with this problem today, but am still looking
for suggestions as to what could be wrong:
 
>Rebooting the phone (by the keypad, or by removing power) will 
>not cause it to re-register, nor will stopping asterisk and 
>restarting it.
>
>If the phone that refuses to register is moved to a completely 
>different location and server, it will begin working again 
>fine.  It can then be moved back to the original 
>location/server and will be fine.

All of our phones use DHCP to get an IP address.  While playing with the
mis-behaving phone today, I forced our DHCP server to give the
non-registering phone a different IP address when it was rebooted.  After
the phone came back up with a different IP address it is working fine again.

I don't understand why that would make any difference, but it makes me think
that something is getting cached on either Asterisk or the Polycom phone
that is causing the problem.

Any help or suggestions would be greatly appreciated!

Thanks,
Eric