GSM And CDMA In The Same Device

[Jim1348]

I apologize in advance for posting here, but I can't seem to find my answer on Howard Forums or other phone sites. I am looking for a suitable Motorola Android smartphone, but I want it to be able to work on both CDMA AND GSM in the United States. I have looked at some worldphone/global phones on-line so far they all seem to have the disclaimer that they work on CDMA in the US, but only on GSM outside of the US. Is that some sort of industry imposed restriction? Also, if there are Motorola phones that will work on both Verizon and AT&T in the United States, is it one or the other at a time or can you actually have service on both GSM and CDMA simultaneously?

[mikegilbert]

Pretty sure the CDMA iPhone 5 from Verizon comes with an unlocked GSM radio on it. I'd confirm the specs though.

[Wowbagger]

The reason they say the phones only do GSM outside the US is that outside the US there isn't much CDMA, only GSM.

I have a Motorola Droid 2 Global which is a quad band CDMA/GSM device, however, it will NOT do GSM in the US due to the way Verizon forced Motorola to program it.

[KitN1MCC]

my old blackberry storm does this

[Jim1348]

Mikegilbert, thanks for the reply. I did run across that this weekend in my research. That is good to know.


KitN1MCC, also good to know.

.....I have a Motorola Droid 2 Global which is a quad band CDMA/GSM device, however, it will NOT do GSM in the US due to the way Verizon forced Motorola to program it.....

So, I wonder if there is a way to un-lock that feature then.

[Wowbagger]

Mikegilbert, thanks for the reply. I did run across that this weekend in my research. That is good to know.


KitN1MCC, also good to know.

.....I have a Motorola Droid 2 Global which is a quad band CDMA/GSM device, however, it will NOT do GSM in the US due to the way Verizon forced Motorola to program it.....

So, I wonder if there is a way to un-lock that feature then.

There are 2 blocks here:
The first is that activating any SIM other than the Vodaphone SIM that came with the phone is locked out by default. However, you can get that block turned off after you've had the account for a while.
The second block is nastier - down in the low-level radio firmware, in the code supplied by Qualcomm, there is a check that basically says:
if (GSM)
if (Site.id != SITE_IS_US)
Use_this_site();
else
FOAD();
endif
endif

And that code cannot be replaced trivially. So the phone will use GSM just fine - just not in the US.

[Jim1348]

Wowbagger,

Thank you for the further clarification. That now bring up more questions in my mind:

-Can it still be unlcoked for use in the United States?

-Lets say you subscribe on CDMA, but are out of CDMA coverage and dial 911 and are in GSM coverage, will it still allow a 911 call?

-Am I likely to run into this issue on ANY Android phone that is both CDMA and GSM then, meaning it will be locked out of GSM Service in the US?

[Wowbagger]

Like I said, the code to allow the phone to use US GSM towers is down the lowest level of the radio firmware, so no, it cannot be unlocked to use US GSM towers - it is as though they do not exist. Therefor, even 911 calls won't go through.

As for "are all phones like this?" - I don't know. My phone is that way because Verizon strong-armed Motorola to do that. Since a CDMA phone has to be tied to the network (not having a separate SIM like GSM does), I would bet that any Verizon-provisioned phone would be that way, but I have no proof of that assertion.

[MP 6.7]

My old Blackberry on Verizon would let me do 911 on GSM if CDMA was unavailable. The 1X and EV icons would disappear and the signal bars would be replaced with a little red "SOS" icon when in that situation. My current phone (Motorola Bionic) doesn't have a GSM radio so it's a non-issue.