ATT 3G on a T-Mobile HD2 - Who says you can't?

[Blairware]

I was lamenting on my lack of foresight, getting a HD2 without researching the different bands that AT&T and T-Mobile use for 3G coverage, when just the other day...

NOTE: This was on a call to AT&T Support and the tech tells me:

a) Once unlocked from TMOUS, I should do a search on "AT&T APN's" and that if I search diligently, I will find APNs on AT&T's network that support HD2 3G Bands

b) AT&T techs, right in his data center have this working.

So I research a bit, and, apart form everyone and his brother professing to be 3G Band experts, and saying all I will see is Edge if I put the HD2 on AT&T. (Which is troublesome, since Wikipedia claims Edge is being dropped to facilitate more 3G bandwidth, so potentially I would lose even THAT).

Here is what official information I could find on the two:

The U.S. T-Mobile network predominately uses the GSM/GPRS/EDGE 1900 MHz frequency-band. T-Mobile's UMTS (3G) service is now active in over 30 major US cities

Further all official documentation states that AT&T uses:
* 850 MHz UMTS/HSPA/HSPA+ 3G
* 1900 MHz UMTS/HSPA/HSPA+ 3G

Finally look at my screenshot, taken from the GSM 3G toggle on the "Settings Tab" of Manila. I am running a NRG ROM (see signature) and I KNOW this is wishful thinking. This screen in particular is no doubt a function of the many devices NRG cooks for, but really, can anyone explain to me why this technically would NOT WORK (other than "just because", LOL)?

 

[Mase_Mase]

AT&T's CEO recently gave an interview and stated that the company's 3G service is being migrated to the 850MHz band with a target date of 2010:

http://www.intomobile.com/2009/02/24/att-3g-network-going-850mhz-nationwide-by-2010.html

For what it's worth, I think the Australian version of the HD2 might have a band that overlaps with US AT&T bands.

 

[Blairware]

Whos gonna buy me one?

AT&T's CEO recently gave an interview and stated that the company's 3G service is being migrated to the 850MHz band with a target date of 2010:

http://www.intomobile.com/2009/02/24/att-3g-network-going-850mhz-nationwide-by-2010.html

For what it's worth, I think the Australian version of the HD2 might have a band that overlaps with US AT&T bands.

Yes, I have been hearing the same. Problem is, I am not likely to fork out $$ for ANOTHER HD2. I just wanted to get the most out of the one I have. Thx!

 

[sirphunkee]

if something like this WAS possible, it would have to be through something like a rogue apn setup on non-standard frequencies on ATT's network...but good luck finding anything like that, it wouldn't be able to remain a secret if it existed. also, if the hd2 had the ability to use those native frequencies, it would have had to have been certified as such by the FCC (which of course it wasn't).

To summarize, the only way to make it happen is if ATT did indeed somehow sneak in alternative-frequency apn's across it's entire network. Let us know how the search for those turns out

 

[ironcrotch]

The U.S. T-Mobile network predominately uses the GSM/GPRS/EDGE 1900 MHz frequency-band. T-Mobile's UMTS (3G) service is now active in over 30 major US cities

Sorry.

http://en.wikipedia.org/wiki/T-Mobile_USA

3G (UMTS/HSPA/HSPA+) service by T-Mobile exclusively uses the AWS 1700/2100 MHz frequency-band, making it incompatible with other existing 3G UMTS/HSPA networks already established in the United States.

 

[speoples20]

Its not physically possible. The hardware would have to be changed. They don't make radio chips with all the bands in it. I see this all the time, some random csr from whatever company says it can be done, but its just not true. Cell phones are designed and made for a specific company. They don't make universal radios and just turn off some bands. They don't exist, though I did read a few months back that Motorala was working on making one.

 

[Svegetto]

Although I understand the reason for your wishful thinking (and you did do some research which is always great), unfortunately it is just that and I'll gladly (though not happily) tell you why.

As you stated "U.S. T-Mobile network predominately uses the GSM/GPRS/EDGE 1900 MHz frequency-band" which is correct (and it also uses the 850 band for edge as well....though this is usually more 'roaming' aka you're using another companies cell tower because tmobile made a contract with them to allow you). You were also correct in stating that "Further all official documentation states that AT&T uses:
* 850 MHz UMTS/HSPA/HSPA+ 3G
* 1900 MHz UMTS/HSPA/HSPA+ 3G"
Also, ironcroth was also correct in quoting that "3G (UMTS/HSPA/HSPA+) service by T-Mobile exclusively uses the AWS 1700/2100 MHz frequency-band" which alone might not answer your question.

So where is the problem if both use 1900 and 850 bands? Well, the problem is that in the hardware, there is a difference between GSM/GPRS/EDGE and 3G/UMTS/HSPA/HSPA+. In other words, you can't use 1900 and 850 Edge frequency of the HD2's radio chip to get 3G (UMTS/HSPA/HSPA+); they are incompatible. This is why phone spects always list both seperatly and not just all the frequencies that it supports.

The above reason alone will make the TmoUSA HD2 incompatible with AT&T's 3G, but there's even more. When Tmobile says that it uses the (for example) 1900 frequency band for Edge, it doesn't actually mean that it uses 1900-1999 frequencies; instead it only uses a part of that spectrum (buying the full 100 frequency range would be expensive so they only buy what they need). Instead they only use maybe something like 1943-1978. And this range will likely not overlap with the frequncies that AT&T uses for their 3G (you can look up the exact values on the internet if you'd like). This second reason is why a european phone which supports 2100 band for 3g will not work on Tmobile's 3G 2100 frequncy (because they don't actually overlap).

Lastly (and I almost forgot to mention this), the screen shot you posted from your ROM can indeed be changed by a cook to whatever they want (though it won't actually make any difference since it all depends on the hardware). However, in this case, it's likely because htc actually made the error and never updated that screen and just used it from their previous builds from previous phones (this was stated on the forums before and I'm sure you'd be able to find it given some searching).

Hope this helps.

 

[d0ug]

To summarize, the only way to make it happen is if ATT did indeed somehow sneak in alternative-frequency apn's across it's entire network. Let us know how the search for those turns out

Quite unlikely, the AWS bands are licensed to TMO, im sure TMO would notice real quick if there were unlicensed cell towers on the AWS band and the FCC would be slapping ATT with fines pretty quick. quite alot of work goes into setting up cell towers and the frequencies each cell segment runs on, If a rouge cell tower went up overlapping TMO's frequencies, all hell would likely break loose as far as customers being able to get usable service in the area.

also as far as the terminology APN's don't operate on a "frequency" an APN is more or less and authentication/proxy server on the data network after the data has transferred over the air interface.

Maybe the best way to think of it is similar to a cell tower being like a wifi access point, and the APN being like an authenticating router/firewall on a standard tcp/ip network. yeah i know its not quite the same, but that might be a simple way to visualize it for those familiar with networking

 

[sirphunkee]

Quite unlikely, the AWS bands are licensed to TMO, im sure TMO would notice real quick if there were unlicensed cell towers on the AWS band and the FCC would be slapping ATT with fines pretty quick. quite alot of work goes into setting up cell towers and the frequencies each cell segment runs on, If a rouge cell tower went up overlapping TMO's frequencies, all hell would likely break loose as far as customers being able to get usable service in the area.

Exactly

also as far as the terminology APN's don't operate on a "frequency" an APN is more or less and authentication/proxy server on the data network after the data has transferred over the air interface.

Maybe the best way to think of it is similar to a cell tower being like a wifi access point, and the APN being like an authenticating router/firewall on a standard tcp/ip network. yeah i know its not quite the same, but that might be a simple way to visualize it for those familiar with networking

Right, very true...I should have said "apn's attached to alternative-frequency radios" Are you a Ham d0ug?

 

[d0ug]

Exactly



Right, very true...I should have said "apn's attached to alternative-frequency radios" Are you a Ham d0ug?

Haha no, though i do have scanners and listen in on HAMs sometimes and have read up on the stuff somewhat. never gotten myself licensed.

On the subject of scanners, there isnt all that much interesting to listen too anymore. Here in tampa the police and sheriff are on analog trunked now, so its impossible to follow anything without a trunking scanner, and about the only other things you can listen to are cabbies, tow truck drivers, aircraft, and hams. I don't even know why scanners still have the 800mhz blocks anymore, analog amps cellular has been dead a few years now. you find lots of digital noise scanning around though, just about everything is transmitted digitally now. i've got an icom R20 that goes from 150khz all the way upto 3ghz

 

[adamhlj]

So why don't you put in an AT&T sim card with a 3G data plan and let us know if you get 3G on your HD2?

 

[jubeh]

Although I understand the reason for your wishful thinking (and you did do some research which is always great), unfortunately it is just that and I'll gladly (though not happily) tell you why.

As you stated "U.S. T-Mobile network predominately uses the GSM/GPRS/EDGE 1900 MHz frequency-band" which is correct (and it also uses the 850 band for edge as well....though this is usually more 'roaming' aka you're using another companies cell tower because tmobile made a contract with them to allow you). You were also correct in stating that "Further all official documentation states that AT&T uses:
* 850 MHz UMTS/HSPA/HSPA+ 3G
* 1900 MHz UMTS/HSPA/HSPA+ 3G"
Also, ironcroth was also correct in quoting that "3G (UMTS/HSPA/HSPA+) service by T-Mobile exclusively uses the AWS 1700/2100 MHz frequency-band" which alone might not answer your question.

So where is the problem if both use 1900 and 850 bands? Well, the problem is that in the hardware, there is a difference between GSM/GPRS/EDGE and 3G/UMTS/HSPA/HSPA+. In other words, you can't use 1900 and 850 Edge frequency of the HD2's radio chip to get 3G (UMTS/HSPA/HSPA+); they are incompatible. This is why phone spects always list both seperatly and not just all the frequencies that it supports.

The above reason alone will make the TmoUSA HD2 incompatible with AT&T's 3G, but there's even more. When Tmobile says that it uses the (for example) 1900 frequency band for Edge, it doesn't actually mean that it uses 1900-1999 frequencies; instead it only uses a part of that spectrum (buying the full 100 frequency range would be expensive so they only buy what they need). Instead they only use maybe something like 1943-1978. And this range will likely not overlap with the frequncies that AT&T uses for their 3G (you can look up the exact values on the internet if you'd like). This second reason is why a european phone which supports 2100 band for 3g will not work on Tmobile's 3G 2100 frequncy (because they don't actually overlap).

Lastly (and I almost forgot to mention this), the screen shot you posted from your ROM can indeed be changed by a cook to whatever they want (though it won't actually make any difference since it all depends on the hardware). However, in this case, it's likely because htc actually made the error and never updated that screen and just used it from their previous builds from previous phones (this was stated on the forums before and I'm sure you'd be able to find it given some searching).

Hope this helps.

Thank you very much. I myself had been wondering why I couldn't get an HTC Desire (honestly, pretty much the only phone I'd change my HD2 for unless a GSM version of the Supersonic becomes available) and have it work in the US at the 2100 frequency.

When I asked before, people would tell me that a phone would have to support both bands (1700/2100) to actually run on T-Mobile because one did HSDPA and the other did HSUPA, but that didn't make sense to me since all you need is a single band frequency to handle both D and U data streams.

Your explanation makes a lot more sense. It's a sad thing, though.

 

[moonchaser]

I remember reading somewhere that a chip manufacturer (motorola?) was working on a all frequency chip. I also read that the inherent problem with that would be the antenna.

It would be awesome to have an all band phone that world travelers could utilize. I love the HD2, I had upgraded from a long time use of a Treo 750. That phone was pretty close (quad GSM, triple umts). However when Tmo rolled out it's 3G on 1700 I was still stuck on edge with the 750.

Finally bit the bullet for an HD2, really like this phone. The 750 seems antique now heheh

 

[d0ug]

I remember reading somewhere that a chip manufacturer (motorola?) was working on a all frequency chip. I also read that the inherent problem with that would be the antenna.

It would be awesome to have an all band phone that world travelers could utilize. I love the HD2, I had upgraded from a long time use of a Treo 750. That phone was pretty close (quad GSM, triple umts). However when Tmo rolled out it's 3G on 1700 I was still stuck on edge with the 750.

Finally bit the bullet for an HD2, really like this phone. The 750 seems antique now heheh

Building a multi frequency chip isnt all that hard. software defined radios have existed for quite some time. basically a simple reprogramming allows it to xmit/rec on a different frequency. the trouble comes in the antenna design. antennas must be designed to work at specific frequencies to be the most efficient at transmitting and the most sensitive at receiving. trying to make a single antenna capable of xmit and rec anywhere in a bandwidth ranging from 700mhz upto say the 2500mhz that wimax uses, is going to make for quite a ****ty antenna at any frequency. When you see the piece of foil antennas in todays phones, they may just look like a simple piece of foil, but a lot of design goes into them to make them work well at the frequencies they need to work with.

I guarantee if you compared the internal antenna of the Euro, AUS and USA HD2 there are slight differences. Ill bet the radio chip in them is for the most part identical, there may be something modified on them to keep people from interchanging the radio roms between them though since that would invalidate any FCC or other country equivalent certification for that phone to operate

Its one thing to run a hacked rom, its something completely different to use an uncertified radio rom. Could cause all kinds of havoc with the cellular network, and get slapped with FCC fines if they could track down your trouble causing phone

 

[moonchaser]

Building a multi frequency chip isnt all that hard. software defined radios have existed for quite some time. basically a simple reprogramming allows it to xmit/rec on a different frequency. the trouble comes in the antenna design. antennas must be designed to work at specific frequencies to be the most efficient at transmitting and the most sensitive at receiving. trying to make a single antenna capable of xmit and rec anywhere in a bandwidth ranging from 700mhz upto say the 2500mhz that wimax uses, is going to make for quite a ****ty antenna at any frequency. When you see the piece of foil antennas in todays phones, they may just look like a simple piece of foil, but a lot of design goes into them to make them work well at the frequencies they need to work with.

I guarantee if you compared the internal antenna of the Euro, AUS and USA HD2 there are slight differences. Ill bet the radio chip in them is for the most part identical, there may be something modified on them to keep people from interchanging the radio roms between them though since that would invalidate any FCC or other country equivalent certification for that phone to operate

Its one thing to run a hacked rom, its something completely different to use an uncertified radio rom. Could cause all kinds of havoc with the cellular network, and get slapped with FCC fines if they could track down your trouble causing phone

Yeah that's on par with what I had read, you do well at explaining it.

Maybe some futuristic worldphone designer would opt for interchangeable external antenna's... I could live with that or maybe multiple builtin foils with a software driven switch between them and the radio... that would be neat. Not holding my breath though...

Interesting on the FCC, hadn't thought of that.

 

[d0ug]

Yeah that's on par with what I had read, you do well at explaining it.

Maybe some futuristic worldphone designer would opt for interchangeable external antenna's... I could live with that or maybe multiple builtin foils with a software driven switch between them and the radio... that would be neat. Not holding my breath though...

Interesting on the FCC, hadn't thought of that.

Thanks, I was just again looking at the spec differences between the euro and TMO HD2s and i really don't know why HTC did not also give the TMO HD2 850/900mhz HSPA/WCDMA to truly make it a world 3G phone. According to the tech specs over at HTC.com, TMO HD2 can already use 850/900mhz for GSM/GPRS/EDGE so the antenna is obviously quite capable of both. The only other frequency the TMO HD2 has to handle that the euro doesn't is 1700mhz

Part of me thinks it was probably done so the HD2 couldn't be used over on AT&T

 

[Svegetto]

Thanks, I was just again looking at the spec differences between the euro and TMO HD2s and i really don't know why HTC did not also give the TMO HD2 850/900mhz HSPA/WCDMA to truly make it a world 3G phone. According to the tech specs over at HTC.com, TMO HD2 can already use 850/900mhz for GSM/GPRS/EDGE so the antenna is obviously quite capable of both. The only other frequency the TMO HD2 has to handle that the euro doesn't is 1700mhz

Part of me thinks it was probably done so the HD2 couldn't be used over on AT&T

It had nothing to do with AT&T, it's because there's a difference between Edge and 3g radio frequency. More than that, there is no phone radio chip that supports all those frequencies and even more so, htc doesn't manufacture radio chips, they purchase them and put them in their phones....just like the majority of the hardware

 

[Shane1975]

Srs wow hd

How do you get SRS WOW HD downloaded onto the HTC HD2?

 

[tai4de2]

a european phone which supports 2100 band for 3g will not work on Tmobile's 3G 2100 frequncy

I think this is incorrect -- the 2100 band support on the HD2 is in fact expressly intended for 3G compatibility in Europe/Asia, and people have reported being able to get 3G in Europe with their US HD2.

1700 == US-only 3G
2100 == Europe, Asia 3G

What's missing, I believe, might be 3G support in certain areas of places like Latin America which may follow US frequencies but don't have T-Mobile USA there to provide 1700 service... e.g., no 2100 and no 1700 either.

 

[jasecloud4]

T-Mobile U.S. uses both AWS 1700mhz and 2100mhz for 3G. The 2100mhz band is used for transmit and 1700mhz is used for receive. Hence the incompatibility with other carriers phones that only operate in one spectrum.

Cheers.

~Jasecloud4