[Verizon Motorola Droid Turbo Q&A, Help & Troublesh] ChazzMatt:
Which "Turbo" do you have? Droid Turbo XT1254 or Moto Turbo XT1225? I assume Droid Turbo because only those people don't also give the model number.

There's two distinct devices (two FCC IDs), sold under three model names:

Verizon Droid Turbo XT1254/U.S. Moto Maxx XT1250 (same phone, same bands, same FCC ID) and

Moto Turbo XT1225/"international" Moto Maxx XT1225 (different FCC ID from XT1254/XT1250, but all XT1225 share the same bands with each other, and are the same phone).

These Droid Turbo/Moto Turbo/Moto Maxx are all under the "Quark" umbrella and except for radio bands are the same hardware, just like all "LG G4" are all the same hardware even though sold by different carriers in different countries.

All the custom ROMs support all Quarks. Custom ROMs over here are for all Quarks, ROMs (kernels, recovery, apps) over in the other Quark forum are also for the XT1254. Most dev work is still over there.

Of course Quarks with GSM/HSPA/LTE carrier SIM cards get simultaneous data/calls -- that's only a Verizon (CDMA) issue. But during phone calls on GSM/HSPA/LTE carriers, you will temporarily drop down to HSPA during the call (for simultaneous data/cellular voice), then jump back to LTE (data only) after the call is completed.

What is "OK" ROM?

We have

7 custom Marshmallow ROMs for the Quark

(maybe 8 depending on how you count) -- they work on ALL Quarks, thanks to our CM dev.

But I'm not familiar with OK ROM. Oh, maybe you mean AOKP? See, I think you are just looking at ROMs here. Yeah, Bliss and AOKP are great, but we have TWO Quark forums. Click that link above and you see all the ROMs. TWRP recovery and BHB27 custom kernel and other ROMs live over in the other Quark forum.

Right now, seems Bliss and Resurrection Remix (Marshmallow) are the two most popular.

Since you don't have the device yet, just to let you know... the XT1254 need paid bootloader unlock via Sunshine($25). Thank Verizon. The other Quarks have free bootloader unlock via code from Motorola website. No, there's no free bootloader unlock for the XT1254. Just believe us.

As for what GSM/HSPA/LTE bands the Droid Turbo XT1254 supports? Well, let's discuss all Quarks. The XT1254 is yours.

The XT1225 and XT1254/XT1250 all share LTE bands 2, 3, 4, 7.

The XT1225 additionally has LTE band 5 and 17 (more bands used by AT&T).

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FCC ID IHDT56PK2

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The XT1254/XT1250 instead has LTE band 13 (Verizon LTE band), plus CDMA bands. While it does have some HSPA bands, there's not as many as in the XT1225.

FCC ID IHDT56PK1

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The Droid Turbo XT1254 has LTE bands 2, 3, 4, 7, 13.

AT&T uses LTE bands 2, 4, 5, 17.

T-mobile uses LTE bands 2, 4, 12

So, of course you can use the Droid Turbo XT1254 on SOME of AT&T's LTE bands or some of T-mobile's LTE bands. Just not all of them!

The problem you will have is in cities like Atlanta, GA where I live where AT&T uses LTE band 17 a lot. In places like that you will have HSPA/HSPA+. In areas where AT&T uses LTE bands 2 and 4 you will be OK. In northern part of Georgia when I drive to Chattanooga, that's mostly LTE band 4, so you would be OK.

So, for AT&T you mostly need a phone with LTE bands 2, 4, 17. (5 is used very little.)

For T-mobile you mostly need a phone with 2, 4, 12.

You have a phone -- the Droid Turbo XT1254 -- with two of those bands: LTE bands 2 & 4.

I have the sibling Quark, the Moto XT1225 -- so I have all of AT&T's LTE bands. ;)

As long as you stay in places AT&T uses LTE bands 2 & 4, you will get LTE. IF you drop down to HSPA, it's probably because you are in an LTE band 17 area or just crappy LTE signal in general.

Same advice with T-mobile and LTE band 12.

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Now on AT&T or T-mobile you will NOT get VoLTE. AT&T restricts that to certain AT&T-branded phones and T-mobile restricts that to LTE band 12. BUT you will still get simultaneous data/cellular voice during phone calls on either carrier.