convert a free AT&T unlocked S5 to run on Verizon?

[jp233]

Hey there all, I got a free AT&T S5 (SM-G900A) from family but unfortunately on 5.0 and was not rooted..... so appears to be stuck as not-rootable.

Anyways, I've got the unlock code from AT&T , but I'm wondering if it's really worth the trouble to even use it,

can i actually flash a Verizon ROM or other good aftermarket ROM (or some other way to get the AT&T junk off the phone, and be able to get Verizon's Backup Assistant and maybe other stuff, to make it like a Verizon phone)?

Or should I just unlock the phone, sell it, and try to find a Verizon phone not on 5.0 so I can root away and actually get what I want.....

Thoughts? Resources?

Thanks...

 

[MattE303]

WHY in god's name would you want Verizon's Backup Assistant???

The S5 is a good phone, If you want to use it, and can get Cyanogen on it, or something similar, I'd do that.

 

[cr6]

1. He won't be able to put Cyanogen on it since it's on OS 5.0 and therefore, unrootable.
2. an AT&T S5 will not work on Verizon regardless of what rom you put on it.
Sell it "as is" and purchase a device that will be compatible with Verizon.
Good luck!

S5 tap'n

 

[FoxKat]

Agreed for the most part. Verizon and AT&T have incompatible cellular telephone systems, so not all the radios in the AT&T variety of the S5 can talk with 100% compatibility on the Verizon towers and vice versa. It is theoretically possible to get some communication working along one or another band but you'll never see performance that would be acceptable.

Verizon is both a CDMA (3G) cellular network for phone calls and data and an LTE (4G) network for high speed data and Voice over IP (VOIP) for phone calls, whereas AT&T is GSM for phone calls and 4G LTE (HSPA+) for high speed data. These two phones talk on different frequency bands and use completely different communication protocols - different languages for regular phone communications, texts and lower speed data.

For comparison (and with no racial implications intended), one could say AT&T speaks Cantonese (GSM - the more global version of cellular radios), Verizon speaks Mandarin (CDMA - primarily here in the US). Even though they are both Chinese (think cellular), languages they are distinctly different and are not mutually intelligible so making phone calls, texting and data communication over the Verizon's CDMA 3G network are out of the question with GSM radios. However, they do both use the same LTE spectrum so you still may be able to use your AT&T 4G LTE device on Verizon's LTE network for data communication and VOIP with a ROM and radio firmware that take advantage of this and theoretically, it could work.

If it's being done for purposes of experimentation and proof of concept one could possibly get it working some, however in the end, the efforts necessary to get any of this working and the lack of 100% compatibility are reasons enough to steer clear of it for all but the developer/hacker community. IMHO I believe it's a better move to sell the phone and get a Verizon version of the same or another phone if you must be on Verizon.

 

[MattE303]

cr6 and FoxKat, my (Verizon) S5 has a setting called Network Mode where the choices are:

1. GLOBAL
2. LTE/CDMA
3. LTE/GSM/UMTS

I always assumed this meant my phone has radios for both network types, is that not the case?

 

[cr6]

Or should I just unlock the phone, sell it, and try to find a Verizon phone not on 5.0 so I can root away and actually get what I want.....
Thanks...

To address your last concern, if you're looking to purchase a brand new device you're going to be hard pressed to find one that doesn't at least have 5.0, in turn making it difficult to root said device.
If you absolutely must have a rooted device you'll either have to purchase a Developer Edition or a Nexus model. If I recall correctly the LG G4 was still rootable, but you may need to verify that on the XDA forum. Otherwise check Swappa for an older device still on 4.4.

S5 tap'n

 

[cr6]

@MattE303 : It has the GSM radio built it, (Verizon originally advertised this as a "world phone") but Verizon has it disabled and I've never come across anyone that has been able to activate it to work on an actual GSM network, past what FoxKat had already mentioned. For everyday reliable use, you're out of luck.
FoxKat will be able to better elaborate.

S5 tap'n

 

[MattE303]

@MattE303 : It has the GSM radio built it, (Verizon originally advertised this as a "world phone") but Verizon has it disabled and I've never come across anyone that has been able to activate it to work on an actual GSM network, past what FoxKat had already mentioned. For everyday reliable use, you're out of luck.
FoxKat will be able to better elaborate.

S5 tap'n

ah, interesting, thanks for clarifying!

 

[Jeffrey]

You got the best advice there is @jp233 .. I agree, sell the phone and get what you want...

 

[FoxKat]

@MattE303 : It has the GSM radio built it, (Verizon originally advertised this as a "world phone") but Verizon has it disabled and I've never come across anyone that has been able to activate it to work on an actual GSM network, past what FoxKat had already mentioned. For everyday reliable use, you're out of luck.
FoxKat will be able to better elaborate.

S5 tap'n

@MattE303 The Galaxy S5 is one of a group of 42 "world phone" models (Smartphones, Tablets, Connected Devices & More - Verizon Wireless), sold for primary operation on Verizon's cellular network and yet are able to communicate on GSM networks while traveling overseas. These phones will communicate on foreign GSM as long as certain requirements are met. See International Travel FAQs | Verizon Wireless for complete information, however in summary you would need to add an International Travel Plan on your Verizon service in order for the phone to activate properly on the GSM network overseas. Alternatively you can add TravelPass to an existing account and be able to use it overseas and pay the per diem rate for use.

As for using it on GSM networks here in the US (unlocking it), I believe @cr6 is correct, Verizon holds the "key" to GSM on that phone (which they have locked down tight), and due to competition they didn't want people buying phones from them, often at deeply discounted cost (i.e. subsidized), and then using it on a directly competing network for service thereby preventing Verizon from recapturing the upfront costs in lost profits through service.

There may be ways to get them working on another network that is not "directly" compatible (i.e. not CDMA), but it's not easy. Here's just one of many videos showing a Verizon S5 working with an AT&T SIM by adding the AT&T APN and changing other advanced settings, though not completely.


Reading the comments below that video, it appears there has been spotty and various levels of success in getting other aspects working.

Here's another one showing an S4 working both for data and phone calls.


In both situations, I don't believe they are running in 4G LTE, but only in 3G (HPSA+). To use the key word from @cr6, they are not "reliable" and so you must keep that in mind.

Here's a Note being used on AT&T, and he's gone into all the setting changes one by one to complete this transition. Again, it's not full 4G, but instead a 3G/4G hybrid and I can't attest to its reliability.

 

[jp233]

Roger all, folks. Thanks a bunch.

Yeah I unlocked the AT&T S5 and will end up just selling it. I guess I was thinking about root just for fooling around and such, I'm not a hardcore dev or anything. I just feel like I should have root for file exploring, used to have to have it for wifi tether but its included on the plan now, I really like TiBu, etc.

Now the question is...... what to get? Find an S5 still on Android 4.4, get one of the Motorola or Nexus ones, or just go all-new and get the S7 or S7 Edge.

My basic requirement is that it must have external storage (S6 is out, Apple is out), great battery life, and I don't want anything gigantic just yet.... a 5" screen is plenty enough.

The ole Razr Maxx is getting....... old. Need more storage than 32gb SD card, and it is getting slow here and then. tough when I have 2 other Razr/maxx which are still usable, one lost GPS and one has a usable cracked screen though.

I've found the zillion text messages are what makes it slow. I delete a ton of texts, it spiffs up nice.

 

[cr6]

You can't go wrong with the new S7, especially with Verizon's payment plans and the fact that it's been out for a little while now, you should find some decent deals. The S5 is still a great device but you'll be hard pressed to find one still on 4.4., unless of course you find one already rooted, but that's always risky buying a used rooted device. Personally I'd go new if you can swing it.
Good luck & let us know what you end up with.

S5 tap'n