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Why won't an unlocked iPhone work on CDMA?

Uguubot

Uguubot

macrumors member
Original poster
Dec 16, 2010
97
5
Minnesota
I know it might change with the new iPhone, but the website says that unlocked iPhone won't work with CDMA networks like Sprint. Which sucks, because I was looking to sell my iPhone 4S to buy the new iPhone when it releases.

Any technical reasons for this?
 
There's no technical reason for it, but the CDMA carriers in the US don't usually allow you to use a phone that you didn't buy from them on their network.

The iPhone software doesn't allow you to switch an iPhone activated on a GSM network to use a CDMA network as a result.
 
Uguubot said:
I know it might change with the new iPhone, but the website says that unlocked iPhone won't work with CDMA networks like Sprint. Which sucks, because I was looking to sell my iPhone 4S to buy the new iPhone when it releases.

Any technical reasons for this?
Click to expand...



Yes there is. It must have an ESN number To work on a CDMA network. which is hard coded onto the circuit board.
 
This is why I hate CDMA. People complained about at&t's lockdown, but verizon and the other CDMA carriers were the ones who had locked down their phones and there was nothing you could do to hack it. You can't transfer from verizon to sprint or vice versa.
Daveoc64 said:
There's no technical reason for it, but the CDMA carriers in the US don't usually allow you to use a phone that you didn't buy from them on their network.

The iPhone software doesn't allow you to switch an iPhone activated on a GSM network to use a CDMA network as a result.
Click to expand...
 
applefanDrew said:
Yes there is. It must have an ESN number To work on a CDMA network. which is hard coded onto the circuit board.
Click to expand...

All iPhone 4S have an ESN/MEID in addition to an IMEI (I think they're usually the same number, too). You can see this even on the sticker on the box of an AT&T iPhone 4S. I doubt there is any actual technical restriction, and it's probably just completely restricted by policy. Although I wouldn't be surprised if Apple disabled the CDMA side in software on GSM phones.
 
Stratus Fear said:
All iPhone 4S have an ESN/MEID in addition to an IMEI (I think they're usually the same number, too). You can see this even on the sticker on the box of an AT&T iPhone 4S. I doubt there is any actual technical restriction, and it's probably just completely restricted by policy. Although I wouldn't be surprised if Apple disabled the CDMA side in software on GSM phones.
Click to expand...

iPhone 4S MEID is the same as the IMEI minus the last number. I believe there are hacks to activate the CDMA portion, but the CDMA network must be willing to activate your iPhone. (Sprint will not allow foreign ESN/MEID on their system. I think the same goes for Verizon.) May have better luck with Cricket or Metro PCS.
 
1080p said:
iPhone 4S MEID is the same as the IMEI minus the last number. I believe there are hacks to activate the CDMA portion, but the CDMA network must be willing to activate your iPhone. (Sprint will not allow foreign ESN/MEID on their system. I think the same goes for Verizon.) May have better luck with Cricket or Metro PCS.
Click to expand...

Ah you're right. I think the last digit is a check digit, on the IMEI.

Some people have activated Verizon iPhone 4's on Cricket, so I suppose we might see someone do something like this eventually...
 
Applejuiced said:
Like said above it has nothing to do with technology.
It's the carrier that won't let it activate on their network.
Click to expand...
According to what I have heard, another reason behind this is because CDMA handsets require some additional baseband programming besides simply entering the ESN/MEID into their systems. While it is theoretically possible to reprogram basebands between carriers, it is fairly technically complex task for store reps to handle. For that reason, Apple pre-programs the handsets designed for Verizon or Sprint at factory, then separates them into different piles when shipping them to retail stores/carriers.

If the above is true, then the reason why it's not possible is simply because the carriers don't want to be hassled with reprogramming phones. It's much easier to try to sell you a new phone then to fiddle with your existing one to make it work with their network, although technologically possible.
 
eastercat said:
Yet apple still cautions anyone with an unlocked phone that it's not usable on cdma networks. Verizon probably makes you jump through so many hoops that you're going to throw your hands up in exasperation and just buy a phone from them.
Click to expand...

Exactly.
They will turn you down so many times and after the first 100 times you will eventually give up:D
 
I was just pointing out that it is possible, contrary to what previous posts were saying.

And, Verizon even has a policy about getting it done. Just have to know the right questions to ask, and move on up the food chain until you find someone who knows what they're doing.
 
It's also possible that I'll be on the cover of vogue, even though I'm 5'4 and overweight. There's possible and there's ice cube in hell possible. I'm saying this is the latter.
anonymouslurker said:
I was just pointing out that it is possible, contrary to what previous posts were saying.

And, Verizon even has a policy about getting it done. Just have to know the right questions to ask, and move on up the food chain until you find someone who knows what they're doing.
Click to expand...
 
eastercat said:
It's also possible that I'll be on the cover of vogue, even though I'm 5'4 and overweight. There's possible and there's ice cube in hell possible. I'm saying this is the latter.
Click to expand...

I've done it. It's quite possible. They support it.

Like I said, you just have to ask the right questions to the right service reps.

It's not rocket science.
 
anonymouslurker said:
I was just pointing out that it is possible, contrary to what previous posts were saying.

And, Verizon even has a policy about getting it done. Just have to know the right questions to ask, and move on up the food chain until you find someone who knows what they're doing.
Click to expand...
So what exactly are the right questions? I have an unlocked 4S and my AT&T contract ended about 2 months ago. I'm planning on switching to Verizon when next iPhone comes out, but if there is a way to convince Verizon to activate my current 4S today, I'm all for it.

I always knew it is in fact technically possible to move 4S between AT&T, Verizon and Sprint, but given that carriers' policies do not allow that and on top of it Apple officially says that factory unlocked will not work on CDMA networks makes it a tough sell.

If anyone has any tips on convincing Verizon, they would be greatly appreciated.
 
I know someone that moved from sprint to Verizon with an iPhone. I didn't know it was such a big deal though. I'll ask him how the process went and post back.
 
Pirate515 said:
So what exactly are the right questions? I have an unlocked 4S and my AT&T contract ended about 2 months ago. I'm planning on switching to Verizon when next iPhone comes out, but if there is a way to convince Verizon to activate my current 4S today, I'm all for it.

I always knew it is in fact technically possible to move 4S between AT&T, Verizon and Sprint, but given that carriers' policies do not allow that and on top of it Apple officially says that factory unlocked will not work on CDMA networks makes it a tough sell.

If anyone has any tips on convincing Verizon, they would be greatly appreciated.
Click to expand...

You cant do that with an AT&T iphone.
Above we were talking about a CDMA iphone 4S from sprint to verizon or the other way.
Not from AT&T to Sprint or verizon. It wont work.
 
Applejuiced said:
You cant do that with an AT&T iphone.
Above we were talking about a CDMA iphone 4S from sprint to verizon or the other way.
Not from AT&T to Sprint or verizon. It wont work.
Click to expand...

This is correct, what I was talking about was only between CDMA carriers.

Even though the 4S does have hardware to support GSM and CDMA networks, different baseband firmware would be required for each.

While technically possible, would definitely require some hacking, and would not fall into that category of Verizon supported activations.
 
anonymouslurker said:
This is correct, what I was talking about was only between CDMA carriers.

Even though the 4S does have hardware to support GSM and CDMA networks, different baseband firmware would be required for each.

While technically possible, would definitely require some hacking, and would not fall into that category of Verizon supported activations.
Click to expand...
If a different baseband firmware was required, then how is it Verizon and Sprint iPhones can operate on GSM carriers (even AT&T and T-Mobile USA if properly unlocked, in addition to non-domestic GSM carriers that it's normally used for) ? I really don't see why this wouldn't be able to work the other way around (4S purchased form/for AT&T, unlocked fully, and working on Verizon or Sprint after convincing them to program the CDMA chip) ?
 
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