[Asterisk-Users] How to restrict access to * for a specific soft/hard phone model?

[Jacek]

Anobody gives me a tip how to recognize what soft/hard phone is in use 
for a call? I would like to allow access to * for those phones which 
have been tested and validated by me, e.g. calls allowed from X-lite but 
not from Linksys PAP2. I want to be sure that every user uses the same 
phone model, for example X-lite.

Thanks!