Caution should be taken when buying off ebay. The esn and imei need to be released by the carrier through the current user.
using an 8350i in Mexico you will likely need to buy a sim from your Nextel carrier in order for it to work along with the proper plan to utilize BBM and data.
Carrier- maybe you need to check before you jump on a thread. the 8350i will work in Mexico on the Nextel network. The 8350i cannot be unlocked. This has been discussed many times.
Top- do a search on 8350i mexco and you will find others that use this bb in mexico.
this blackberry should work on mexico as the nextel letters on the bottom are grey and not yellow. ask the seller if he had it with nextel mexico, if its reported stolen or lost it will not work (only walkie talkie). bb messenger its the only thing that i havent tried on an american 8350i (Supposedly BB PIN is tied to the account and only mexican blackberries are allowed to PIN). messages will work with the right service books.