ALso note that every mobile user should note down IMEI Number of his handset in seperate diary, its printed on backside of mobile phone, or u can dial *#06# and u will get tht number, whenever any one loses his cell phone they give this number at the concerned police station few police stations have got that technology to track cell phone from imei number u provide.Mobile network operators can block the IMEI no, once that IMEI Number is blocked mobile phone is useless no sim card will work in tht phone, but tht technology is yet to come in india.
but there is also 1 drawback some highly technically qualified theives can change IMEI Number with special tools , but tht is very rare at least in india that is wht i think.
hope this proves useful.