I tried to sim unlock my phone through this method
How to SIM unlock Samsung Galaxy S4 SGH-M919 (tested - works) - Updated: 7/2/13 - xda-developers




I did follow all the steps but when I insert another sim (T-mobile), I got an "Invalid Sim" pop up message.


after searching around i found this thread
SIM Unlock for International GSM/WCDMA [SPH-L720] | Android Bilgini





and came to the conclusion that cricket might also be locking the GSM functionality of the s4.

is there anyway i can make other gsm sim card work on my cricket galaxy s4?