Roaming Bands from Sprint to Tmobile


I have a question in regards to domestic roaming and the bands required. If I have the EM7455 setup for Sprint Bands using the following:

at!band=0D,“Sprint (All)”,0,0000010003000000

And I lock the band to Sprint(All) and let’s say we are in an area where the domestic roaming agreement is with T-Mobile who uses band 12 etc. Does the modem need to have those bands flashed as well and if so, how do you set/lock the bands so that it will roam over to those.

As from what I understand if I lock to 0D in case above, then the modem wouldn’t look for band 12… Do I need to combine the custom binaries to include all the bands I want as an “All” setting?

Thank you in advance!