No, you cannot use a T-Mobile or AT&T phone on Cricket, and you cannot use an unlocked phone, or any GSM phone on Cricket.

Cricket uses a technology called CDMA. T-Mobile and AT&T use a technology called GSM. These two aren't interchangeable. In order to use Cricket, you will need a CDMA device. The national carriers that use CDMA are Verizon Wireless and Sprint. MetroPCS, along with some other regional carriers use CDMA.

For information on getting a CDMA phone to work on Cricket, click on the following link: http://www.cricketusers.com/forum.php#device-central