With Contract Locked Phone

Um.  Super awkward way of wording the question. 

I think you better reword it and try again

Hello BC1234, we're here to help with a locked phone on installment.

In order for an AT&T device to work with cricket it will need to be unlocked. To unlock the phone, it will need to be paid off. Once the device is paid off, you can unlock and use it with another provider. 

Feel free to reach back out if you have any further questions or concerns.

Thank you for visiting AT&T Community Forums!

Actually @ATTHelp  is wrong.  Phones locked to AT&T will work on Cricket Wireless since it’s a MVNO that uses the AT&T network.  In fact, Cricket is owned by AT&T.

In order for an AT&T device to work with cricket it will need to be unlocked.

Well, that is not true. A locked AT&T phone will work on AT&T MVNO's without being unlocked. The reverse is not true.

However, AT&T is enforcing its unpaid device policy. That policy means that a device that is being financed on AT&T cannot be used on any account other than the one it is being financed on. This means it is blocked to be activated on any other AT&T account, so far that seems to include AT&T prepaid and AT&t's entirely owned subsidiary cricket.

But because of the awkward way the original poster has stated his question, it's impossible to know whether or not this phone is an unpaid device, or simply came from AT&T originally and has been paid off. Also cannot tell if they're asking if they can finance a phone on AT&T and use it on Cricket, which they cannot.