asterisk users - Jul 2006 - Sip phone settings according to logged in user

Hi all !
I am planing to set up around 20 SIP Phones which will be purchased in 
one bunch, I am more or
less free of choice.
I wonder if anyone knows sip phones which allow configuration upon 
login. The following scenario:
User logs into any phone and the settings of the phone are always the 
same. Meaning individual key
assignement is always the same.

Is this possible with asterisk in combination which any phone or do I 
require special phones.

Nik