Ok. I saw this forum in an article (lifehacker? gizmodo?), wandered over, and realized I might be able to ask a question here that's been bugging me for a few months.
A preface: I'm not an electronics expert. Hell, I'm not even a beginner. Closest I've ever gotten to understanding electronics is being able to put computer parts together to build a PC. I *think* I know the basic functionality of a few basic parts (resistors, capacitors), but pretty much any terminology is going to be something I'm going to have to Google feverishly just to understand. (Hell, I was reading your rules, and I had to spend two or three minutes Googling "LED to mains" just to figure out why it was against your rules to talk about. And I'm still not entirely certain why. Fire hazard is my guess.)
Anyhow... this is going to require a bit of background explanation.
Cellphones. Specifically GSM (as opposed to CDMA) cellphones, in this case. There is, so far as I understand it, two (or maybe six to ten) radios in a cellphone.
The first kind of radio is the actual GSM radio (operates on bands that are described as 850/900/1800/1900, and I'm pretty sure those are MHz). Most phones come "quad-band" like that, as different carriers in different locations have rights (owned or rented) to specifically only one or so of those four bands, and those GSM bands are the ones that the phone uses to actually "talk" for phone conversations. For example, in America, 850 and 1900 are the used frequencies.
Almost all phones come with the full set of four frequencies, and I think it's a very rare situation (Brazil only, I think?) where any other frequencies are used for standard phone operation (1900/2100 in Brazil, I think).
None of that matters, since all phones (that I'm looking at) come in quad-band GSM style that's compatible almost anywhere I'm likely to go.
2G data networks also operate on GSM bands and frequencies. However, 2G is slow. A bit like a dial-up modem.
Let me be clear: Everything above relating to GSM is pretty much unrelated to what I'm trying to ask, and I only included so I can be specific about it NOT being what I'm asking about. I've asked this question elsewhere, and it took a couple days for people to figure out I wasn't talking about GSM, so I'm being clear in advance. GSM is not what I'm talking about.
However, their data networks (specifically what's described as "3G") operate over something called "UMTS" or sometimes "CDMA2K".
This (apparently) requires a separate radio in the phone. A second one, in addition to the GSM radio. I don't know why. All I know is that phones seem to come with a few particular sets of frequencies they can talk on:
900/1700/2100 MHz
1700/2100 MHz
900/2100 MHz
850/1900 MHz
are common sets of frequencies.
Note, that out of those combinations of frequencies, there isn't a single combination that includes all four possibilities: 850/900/1700/2100. No phone I've ever looked at supports all four, and no one I know has ever been able to find a phone that supports all four.
Specifically, either a phone has 850, or it has 2100, but never both, and never all four.
This is a problem, because AT&T is only compatible with 850/1900, and T-Mobile is only compatible with 1700/2100.
Which means that if you buy a cellphone, your 3G service will ONLY work on one carrier, and not the other. Ever. (And despite what you've heard about "unlocked" cellphones, "unlocking" only applies to the GSM radio. So it doesn't "unlock" 3G service for you so you can use it on the competition's carrier.)
I'm fairly certain ("common" sense, talking) that this isn't due to technical limitations. I've been lead to believe that it's actually more to do with cellphone companies having the legal backing to where they need to approve every cellphone sold for the USA, and they'd never approve of a device made for the competition. So, for example, AT&T will only approve of a cellphone that supports radios that talk on 850/1900. So any phone that's built like that won't on T-Mobile's 3G networks. Same is true for the reverse.
Now, to my questions (finally).
First, what the <snip>? Anyone know, or have backstory on this crap? Is this design simply greed, or is there more to it than that?
Second, is there anything at all that I can do?
I'd like to avoid slapping down $700 for an unlocked GSM phone that I still can only use 3G on one single network, and never any other network. It's like signing a contract to stay with that network for the life of the phone, even without the contract. And yes, before you ask, I am going to be aiming for an unlocked cellphone to use for service with no contract. The phone I have currently is exactly that, with an AT&T subsidiary providing service with no contract. It's just also a nine year old phone, and I'd like to upgrade without signing my soul away.
Is there a way for me to retune the radio? Install a second one, with a switch to flip between them? Some other solution I'm not thinking of? I'm definitely not looking for a walkthrough (just yet), so it's probably best not to spend a few hours coming up with diagrams, etc, as I don't even have the phone I'm going to upgrade to yet, but I would like to know my options ahead of time.
A preface: I'm not an electronics expert. Hell, I'm not even a beginner. Closest I've ever gotten to understanding electronics is being able to put computer parts together to build a PC. I *think* I know the basic functionality of a few basic parts (resistors, capacitors), but pretty much any terminology is going to be something I'm going to have to Google feverishly just to understand. (Hell, I was reading your rules, and I had to spend two or three minutes Googling "LED to mains" just to figure out why it was against your rules to talk about. And I'm still not entirely certain why. Fire hazard is my guess.)
Anyhow... this is going to require a bit of background explanation.
Cellphones. Specifically GSM (as opposed to CDMA) cellphones, in this case. There is, so far as I understand it, two (or maybe six to ten) radios in a cellphone.
The first kind of radio is the actual GSM radio (operates on bands that are described as 850/900/1800/1900, and I'm pretty sure those are MHz). Most phones come "quad-band" like that, as different carriers in different locations have rights (owned or rented) to specifically only one or so of those four bands, and those GSM bands are the ones that the phone uses to actually "talk" for phone conversations. For example, in America, 850 and 1900 are the used frequencies.
Almost all phones come with the full set of four frequencies, and I think it's a very rare situation (Brazil only, I think?) where any other frequencies are used for standard phone operation (1900/2100 in Brazil, I think).
None of that matters, since all phones (that I'm looking at) come in quad-band GSM style that's compatible almost anywhere I'm likely to go.
2G data networks also operate on GSM bands and frequencies. However, 2G is slow. A bit like a dial-up modem.
Let me be clear: Everything above relating to GSM is pretty much unrelated to what I'm trying to ask, and I only included so I can be specific about it NOT being what I'm asking about. I've asked this question elsewhere, and it took a couple days for people to figure out I wasn't talking about GSM, so I'm being clear in advance. GSM is not what I'm talking about.
However, their data networks (specifically what's described as "3G") operate over something called "UMTS" or sometimes "CDMA2K".
This (apparently) requires a separate radio in the phone. A second one, in addition to the GSM radio. I don't know why. All I know is that phones seem to come with a few particular sets of frequencies they can talk on:
900/1700/2100 MHz
1700/2100 MHz
900/2100 MHz
850/1900 MHz
are common sets of frequencies.
Note, that out of those combinations of frequencies, there isn't a single combination that includes all four possibilities: 850/900/1700/2100. No phone I've ever looked at supports all four, and no one I know has ever been able to find a phone that supports all four.
Specifically, either a phone has 850, or it has 2100, but never both, and never all four.
This is a problem, because AT&T is only compatible with 850/1900, and T-Mobile is only compatible with 1700/2100.
Which means that if you buy a cellphone, your 3G service will ONLY work on one carrier, and not the other. Ever. (And despite what you've heard about "unlocked" cellphones, "unlocking" only applies to the GSM radio. So it doesn't "unlock" 3G service for you so you can use it on the competition's carrier.)
I'm fairly certain ("common" sense, talking) that this isn't due to technical limitations. I've been lead to believe that it's actually more to do with cellphone companies having the legal backing to where they need to approve every cellphone sold for the USA, and they'd never approve of a device made for the competition. So, for example, AT&T will only approve of a cellphone that supports radios that talk on 850/1900. So any phone that's built like that won't on T-Mobile's 3G networks. Same is true for the reverse.
Now, to my questions (finally).
First, what the <snip>? Anyone know, or have backstory on this crap? Is this design simply greed, or is there more to it than that?
Second, is there anything at all that I can do?
I'd like to avoid slapping down $700 for an unlocked GSM phone that I still can only use 3G on one single network, and never any other network. It's like signing a contract to stay with that network for the life of the phone, even without the contract. And yes, before you ask, I am going to be aiming for an unlocked cellphone to use for service with no contract. The phone I have currently is exactly that, with an AT&T subsidiary providing service with no contract. It's just also a nine year old phone, and I'd like to upgrade without signing my soul away.
Is there a way for me to retune the radio? Install a second one, with a switch to flip between them? Some other solution I'm not thinking of? I'm definitely not looking for a walkthrough (just yet), so it's probably best not to spend a few hours coming up with diagrams, etc, as I don't even have the phone I'm going to upgrade to yet, but I would like to know my options ahead of time.
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