I have if you are interested solved this .... I used http://wiki.freeradius.org/Mac-Auth as a guide.... In policy.conf I have added.... rewrite_data_sim_users { if (Calling-Station-Id =~ /(894420000[0-9]{10})/i) { update request { User-Name := "%{Calling-Station-Id}" User-Password :="SIMUSER" } } else { noop } } In sites-available/default I have changed: authorize { preprocess rewrite_data_sim_users Which means IF you get a Calling station in a particular format it changes the username to thie calling station ID and in my case also changes the password... I then have users setup as normal with the username as the SIM ID and a password of SIMUSER They may be a better way... but this seems to work :-) Richard