N910P - I have MSL code but no prompt to unlock? please help

Hi All,
Please help.

Goal:
- unlock N910P for domestic US (I have MSL code from Sprint)
- do not want to root

Details:
- account and phone is paid
- Sprint gave me MSL saying it is my unlock code
- 5.1.1
- has been reset to factory and cleared cache
- I watched a few videos saying that I need to put a different carrier sim in and it will prompt for the MSL code to unlock
- I have tired 4 sim from T-Mobile and AT&T, 2 are working sim from working phone... none will prompt for code
- I tried ##3282# which get me to manual settings but I am not sure if I should mess with it
- invalid sim for T-Mobile and AT&T but works fine for Sprint
- I read that it may work with Kit Kat but I cannot downgrade without root

Thank you all in advance.

Please let us not get into the debate of carriers and GSM/CDMA. I just need help with the unlock portion. Thank you again. :highfive: