I was given a brand new AT&T HTC One M9. It came with the code & instructions from AT&T on unlocking the phone. Now I am new to all this stuff but I thought that I could bring this Gsm cell to other carriers who might offer cheaper services than AT&T. I had chatted with Cricket extensively prior to this and was told outright that since being purchased by AT&T that their customers have access to the AT&T towers so I would basically get the service and quality of service any AT&T customer would get (as far as range, connectivity, quality of calls, etc). Now having the phone & the IMEI number I went back to Cricket & what I found was, sure I can get their sim card and go with them but I would only get access to 3G not 4 and definitely not 4G LTE! So I said to the gal "so you punish customers for not buying the phone from you by only giving them access to 3G" and she replied "exactly".
Is this true? If so why haven't I read one thing about this and I read myself blind before thinking I might go the route of an unlocked phone. If that's the case I could buy a 3G cell for $50 vs having a $650 phone since I'm not utilizing its full capabilities!
Can someone help me out here?
Maybe make some suggestions?
I'm just really surprised that if you bring your own phone to a carrier if all they let you have is their 3G network why are unlocked phones so hot and why haven't I read anything about this?

See More: Unlocked cell phones only allowed access to 3g?