Help Buying phone question & Imei

[chargersrool]

I plan on buying a phone from someone off of craigslist and just want to know what steps I should take to check whether its legit or not.
http://fortmyers.craigslist.org/lee/mob/4812533981.html
I hear at&t phones work with cricket so i made an arrangement to meet at the cricket store. Can they check whether the phone is reported stolen? Where will the imei # be on the galaxy s5?
I should disregard the imei# on the box because the phone might have a different imei correct?
Thanks for all the help in advance!

 

[mikedt]

The usual advice when buying used phones from Craigslist, is to meet with the vendor at the carrier store, e.g. AT&T, so that they can verify that the phone is actually theirs to sell, and it hasn't got any outstanding contract defaults on it, which could very well cause it to be IMEI blacklisted. The IMEI on an S5 will be stamped on the back of the phone itself, under the battery, and by doing *#06# from the dialler, the numbers must match. It should also match what's on the box as well, if that particular phone came in that box.

 

[chargersrool]

At&t doesnt check whether the phone is registered or reported stolen, they say they can only check if the phone is activated. Cricket will allow me to check though.
Whats the downside to buying a tmobile phone and using it with cricket as opposed to using an at&t phone with cricket?
I hear in some cases, unlocked phones sometimes dont allow you to text or use internet.