no, not really, very few networks will pass anything to you in the http headers likes a valid msisdn or imei number which you could then ban.
the only thing to do would be to thoroughly investigate the headers that the cellphone / device is sending and see if there is anything in there that will tie you in with a particular handset.
(apologies for posting this, i just relised the date is last year, i saw 08 and thought it was this month....)
