Database Users

GSM vs CDMA

First of all, thanks to all who have already done what I have not been brave enough to do...which is purchase a Shift without the assurance of definitely being able to make it a cell phone. If this device was talking out of the box I'd have one already. Now that it seems like regular voice calls are going to become possible, which Shift would the experts recommend? I wonder how HTC is going to interpret the spike in sales once calling is a reality!

GSM v CDMA
Personaly i'd go GSM... (in fact i did)
mainly tho because Australia doesn't have a CDMA network anymore

best description
http://www.google.dk/search?source=ig&hl=da&rlz=&q=GSM+vs+CDMA&btnG=Google-søgning&meta=

Thanks for the replies. I'm leaning towards GSM since I already have AT&T service and I seem to get better coverage than some of my Sprint friends. I guess what I'm really interested in is if the Shift Project Members (SPM's!!) are working with GSM or CDMA units. I would assume GSM, since they came out first...would a CDMA unit to tinker with help the development progress?

They are using GSM versions.
I understand the keyboard layout is much better for americans on the CDMA version. I'd be interested to know when a USA GSM version is planned on being released.

More questions...
Aside from the cosmetic differences, (color, attached case), and the keyboard layout, I've been hearing and reading about build quality differences too. Some reviewers who have had an opportunity to test both models say that the CDMA version feels a little more solid than the GSM. Could this be due to small build revisions or maybe just be happening by chance? Anyone here gotten their hands on both?

HIgh tech question ?

Hello see all the nice wonderful phones around the world and her in the US we are more or less locked out to a few by the fu.... Provider supplied models month later.
Locked around and saw there are 98% HTC Magic and Hero with UMTS 900/2100 mhz. Also a few with a UMTS 850/1900 for the ATT slaves. It is for me not realistic that HTS build a whole new model for each little US player.
I'm sure there is a quadband UMTS but do to FCC regulation and business restriction for the US market HTC jsut block those frequency.
This would be a more or less usefull patch to make those MOdels from the rest of the world also useable in the USA/Canada.
IS there someone who can confirm that HTC built just for this few US guys a total different hardware or my theories with the blocked Feature deep in the hardware.
Thanks

They dont have to build an entire phone to operate in diferent bands...so i guess its hardware related(just the modem i think) with proper software(radio protocol) to go with it.
If it was just software related or some kind of block in the hardware it would already been bypassed by someone in here...my guess.

Is HSDPA/UMTS band a software issue?

Hi guys, I don't know if this is a basic question but I have to ask it since I haven't find an answer yet...
Can I modify the HSDPA/UMTS band via ROM or SPL update?
I bougth a HTC T-mobile myTouch (1700/2100 MHz bands, UMTS/HSDPA) but later I realized that here in CHILE my provider uses the 850/1900 band for 3g .
So, can I do somethig to make it work here or is it a matter of hardware?
Thanks

birutilla said:
Hi guys, I don't know if this is a basic question but I have to ask it since I haven't find an answer yet...
Can I modify the HSDPA/UMTS band via ROM or SPL update?
I bougth a HTC T-mobile myTouch (1700/2100 MHz bands, UMTS/HSDPA) but later I realized that here in CHILE my provider uses the 850/1900 band for 3g .
So, can I do somethig to make it work here or is it a matter of hardware?
Thanks
Click to expand...
Click to collapse
No you cant change ur radio bands with software, its a hardware issue and im afraid your stuck with what you got, even flashing a new radio wont change things . . . sorry

it's too different versions of the qualcomm cpu's which makes the band difference
it's hardcoded inside the cpu

You should have bought the Canadian/Rogers version of the phone.
Fvcking HTC builds 3 versions of the phone (mytouch, rest of world, Canada) and people like you and me get fvcked. We have to pay an extra $150 to get the canadian version.
Let it be a lesson: do NOT buy HTC! Acer, Dell, Apple ... they all build phones that work everywhere. NOT HTC.

Rudegar said:
it's too different versions of the qualcomm cpu's which makes the band difference
it's hardcoded inside the cpu
Click to expand...
Click to collapse
Actually the CPU (Qualcomm MSM7201a) is capable of supporting five different UMTS frequency bands, however only three at once. Those bands again are indeed preset by the built-in RF chips, so there is no chance of changing frequencies.
Here's the datasheet of the MSM7200 (identical to the MSM7201a in terms of RF support) with an overview of possible RF chip configurations at the bottom of page 3: http://www.ent.eet-china.com/PDF/2007FEB/DTCOL_2007FEB15_AVDE_RFR_AN_01.pdf

inquisitor said:
Actually the CPU (Qualcomm MSM7201a) is capable of supporting five different UMTS frequency bands, however only three at once. Those bands again are indeed preset by the built-in RF chips, so there is no chance of changing frequencies.
Here's the datasheet of the MSM7200 (identical to the MSM7201a in terms of RF support) with an overview of possible RF chip configurations at the bottom of page 3: http://www.ent.eet-china.com/PDF/2007FEB/DTCOL_2007FEB15_AVDE_RFR_AN_01.pdf
Click to expand...
Click to collapse
Whether a specific band is supported or not in a particular RF topology also depends on the type of RF amplifiers coupled with the baseband IC. Traditionally HTC has been using universal amplifiers for 2G/2.5G hence all recent phones support GSM/GPRS/EDGE on any frequencies. Due to Qualcomm vs. Broadcomm patent lawsuits, they had to stop using universal amplifiers for 3G around 2006, hence most modern phones only support WCDMA/UMTS frequencies that they have individual amplifiers for.
I think it's not HTC specific, any vendors using Qualcomm MSM basebands are doing this as well. So the bottomline is - in most cases it's a hardware issue. In some rare cases (when universal or multi-frequency WCDMA amplifier is installed) frequencies are disabled in software. I can't recall any HTC device that would have this kind of software only limitation.

Wow Very informational posts
Thanks Guys!!!
Hey I'm an old (ancient pre-Intel <BG>) micro hacker
but fairly new to phones. I'm currently very happy with
my cooked AT&T Pure/TopAz with the Tess Leo 1 Rom
I've had most every model of HP IpAQ upto the 4700s
So the PPC side is pretty comfortable for me.
I'm an old programmer with EE background
But really ready to try and get my teeth into the radio side
of phones just trying to understand enough to make some
resonable qualitative and quantitative benchmarks on some these radios
Maybe more to the point is understand if so and so's great looking nice
new task bar should and is properly displaying "3G" or "H" or ?)
But its been hard sorting the Euro vs US and GSM vs CMRS
Phone info.
Can anyone suggest a good "newbie guide" ? or any source of info
(I kinda hate the term "for dummies" but.... )
to the radio end, signal strength, band, networks etc ?
Sorry if this has been asked a million times or its only "two posts" away
but the amount of info here is great! but the s/n is NOT so great <BG>
Thanks Alot
Kenn Lynch
Hey is there a spell checker in this xda forum?
my apologies
I love my phone

if you are on a pc most internet browsers these days got their own spellchecker

Spell check thanks
You know its amazing what some people consider "most" Web Browsers
I was thinking "largest" web browser (Internet Explorer 8.XX on XP)
Spell checking is not natively included, so all my checking has been with
local docs or remotely using the web pages own checker for web based mail and forums.
So I started thinking no wonder this guys name starts with "Rude"
But I looked around and there is a free plug-in for IE called ieSpell.
I seldom bother with the other browsers so I can't say if
spell checking is included right "out of the box" in them either.
but I just installed ieSpell here and it hyphenated "plug-in" nice and easy
Thanks
when you are right you are right
Guess you can teach and old dog <BG>
KJL

Hd2 on at&t

I have a hd2 tmobile usa version, i need a At&t friendly Nand rom. Whats the best rom out there for At&t????
Sent from my Desire HD using XDA App

as far as I know any NAND Android ROM should work on AT&T as it is not the ROM that controls this but a combination of you sim card, APN settings, and you having your HD2 sim unlocked. Wait for more replies though as I do not use AT&T and it might actually be a ROM out there that has certain things adjusted for AT&T, but what that might be I do not know.

This is true, the ROM does not control the radio. There are methods of flashing the radio to a different version, one that may work for the AT&T 3G bands. I am looking them up, but that is how you would flash the device to change the radio.
Hardware wise, the GSM module does support all world wide bands but what makes then different from one HD2 from one carrier ot another is the firmware version that is used in the phones that make them work on the network's bands. Correct me if i am wrong though.

TKETZ196 said:
This is true, the ROM does not control the radio. There are methods of flashing the radio to a different version, one that may work for the AT&T 3G bands. I am looking them up, but that is how you would flash the device to change the radio.
Hardware wise, the GSM module does support all world wide bands but what makes then different from one HD2 from one carrier ot another is the firmware version that is used in the phones that make them work on the network's bands. Correct me if i am wrong though.
Click to expand...
Click to collapse
Untrue my friend, the T-Mobile HD2 only supports the bands used by T-Mobile for 3G. If you sim unlock the T-Mobile HD2 you can use the device with other carriers but you will only get Edge for a data signal as the hardware only supports the T-Mobile 3G bands. There is a model of the HD2 that supports a different 3G band the same ones AT&T uses in the US, it is the Australian model that Telstra a Australian cell carrier released as they use the same bands as AT&T. go to "Official HD2 T9193 (Telstra 850Mhz) Discussion Thread" and you can learn more about it. I also saw your other post in another thread about trying to help your friend out getting 3G on his HD2 using AT&T. Unless he is willing to buy a Telstra HTC HD2 T9193 or have his T-Mobile HTC HD2 T8585 worked on to switch out the hardware for the hardware in the T9193 then he will never getb 3G with AT&T.

Just to answer your question, every rom is an AT&T friendly ROM, meaning, they'll allow you to talk, text and surf the internet.
What you DONT have is AT&T 3G on your tmous HD2. You'll be stuck with EDGE speed.

Thank you all 4 your help,greatly apreciated!! I'm in puerto rico where tmobile is still on Edge. But for some reason tmobile is still alot faster when it comes to receiving & sending MMS than At&t on this phone. Currently using Coredroid 1.5
Sent from my Desire HD using XDA App

its interesting they would use different hardware GSM modules for the slightly different models. I would think the radio firmware version woudl take care of that. Thanks for clarification. I assumed that all GSM modules would be built the same way.

Sadly they are not, this in my opinion is just cellular carriers trying to keep you locked to their networks cause the know most people don"t want to have to buy another device when changing carriers if they already have a good device. So they make it were branded devices can only utilize high speed data with it's intended carriers network. I think this is unfair to consumers, but again just my opinion.

T-Macgnolia said:
Sadly they are not, this in my opinion is just cellular carriers trying to keep you locked to their networks cause the know most people don"t want to have to buy another device when changing carriers if they already have a good device. So they make it were branded devices can only utilize high speed data with it's intended carriers network. I think this is unfair to consumers, but again just my opinion.
Click to expand...
Click to collapse
I think there is technical reason. The various carriers have very different technologies. Even AT&T uses a different 3G network than T-Mobile, despite the fact that both are GSM. Sprint and Verizon use non GSM technologies that are even more different. When a device manufacturer makes a certain model, there is only so much room inside, and unless one wants a really thick and heavy device, a choice has to be made as to which hardware goes into the phone.
I'm not saying that they don't want you to stay on their network - they do, which is why they have those 2 year contracts in exchange for buying a discounted phone. But I don't think that is why the hardware is different.

stevedebi said:
I think there is technical reason. The various carriers have very different technologies. Even AT&T uses a different 3G network than T-Mobile, despite the fact that both are GSM. Sprint and Verizon use non GSM technologies that are even more different. When a device manufacturer makes a certain model, there is only so much room inside, and unless one wants a really thick and heavy device, a choice has to be made as to which hardware goes into the phone.
I'm not saying that they don't want you to stay on their network - they do, which is why they have those 2 year contracts in exchange for buying a discounted phone. But I don't think that is why the hardware is different.
Click to expand...
Click to collapse
Point taken
I would go further with the discussion but I do not want to hijack this thread.

use all 700MHZ lte phones on any network

OK, we all know about Verizon using lower spectrum and AT&T using upper spectrum of 700MHZ but i could never understand how HARDWARE WISE they can make a radio that would only support such a thing, I am under impression that it is the software optimized for using either upper or lower spectrum and if block the other half. I just read how flashing correct radio enabled AT&T GALAXY NOTE to be used on t-mobile, i am not an expert nor i have resources, but has anyone attempted to flash verizon radio on at&t phone or vice versa and see if phone is actually capable of running on both networks? Please explain me if there is any flow in my understanding or is it actually feasible? would be great to break monopoly of at&t and Verizon over their LTE phones even though they utilize same 700MHZ band.

nakamoniel said:
OK, we all know about Verizon using lower spectrum and AT&T using upper spectrum of 700MHZ but i could never understand how HARDWARE WISE they can make a radio that would only support such a thing, I am under impression that it is the software optimized for using either upper or lower spectrum and if block the other half. I just read how flashing correct radio enabled AT&T GALAXY NOTE to be used on t-mobile, i am not an expert nor i have resources, but has anyone attempted to flash verizon radio on at&t phone or vice versa and see if phone is actually capable of running on both networks? Please explain me if there is any flow in my understanding or is it actually feasible? would be great to break monopoly of at&t and Verizon over their LTE phones even though they utilize same 700MHZ band.
Click to expand...
Click to collapse
Certain chipsets with an integrated radio/modem support multiple bands. Like you said, in the case of the Note, XDA devs were able to flash a different modem that told the radio to tune to a different frequency that it supported. Same with the Skyrocket, and, if the T-Mobile SII had an LTE mode, that would have worked too. But not all chipsets can do multiple frequencies on one chip.

Well you'll have a problem of dealing with a CDMA phone trying to run on a GSM network primarily. I think Verizon's system has to verify you're on their primary CDMA network then allow you to connect to their LTE network. Where as an AT&T phone would just connect you to their GSM and then it bumps up to LTE. My speculation is that if you connect a Verizon World Phone with LTE on AT&T with the correct radio it MIGHT work. But it won't work the other way around as AT&T's phones don't have CDMA (which is used to verify and connect you to the LTE network)

ChpStcksRlz said:
Well you'll have a problem of dealing with a CDMA phone trying to run on a GSM network primarily. I think Verizon's system has to verify you're on their primary CDMA network then allow you to connect to their LTE network. Where as an AT&T phone would just connect you to their GSM and then it bumps up to LTE. My speculation is that if you connect a Verizon World Phone with LTE on AT&T with the correct radio it MIGHT work. But it won't work the other way around as AT&T's phones don't have CDMA (which is used to verify and connect you to the LTE network)
Click to expand...
Click to collapse
You will never get a CDMA phone to work on a GSM network or vice versa (aside from global CDMA phones with SIM slots for GSM roaming). LTE phones on Verizon use a their own authentication that's separate from their CDMA-only 3G phones. With the LTE phones, there is no ESN/MEID associated with the device; it's the SIM that is authenticated and then the phone attached to it can use it to transmit and receive data, texts, and calls.
But that's besides the fact; CDMA and GSM are more than just frequencies; they're two different methods on how a phone communicates with towers. CDMA is Code Division Multiple Access, and GSM is based off of TDMA, which is Time Divided Multiple Access. It's kind of like saying, because two people are Chinese, they will both speak one dialect, which in fact there are two; Mandarin (GSM) and Cantonese (CDMA) which are similar but different.

Product F(RED) said:
You will never get a CDMA phone to work on a GSM network or vice versa (aside from global CDMA phones with SIM slots for GSM roaming). LTE phones on Verizon use a their own authentication that's separate from their CDMA-only 3G phones. With the LTE phones, there is no ESN/MEID associated with the device; it's the SIM that is authenticated and then the phone attached to it can use it to transmit and receive data, texts, and calls.
But that's besides the fact; CDMA and GSM are more than just frequencies; they're two different methods on how a phone communicates with towers. CDMA is Code Division Multiple Access, and GSM is based off of TDMA, which is Time Divided Multiple Access. It's kind of like saying, because two people are Chinese, they will both speak one dialect, which in fact there are two; Mandarin (GSM) and Cantonese (CDMA) which are similar but different.
Click to expand...
Click to collapse
some CDMA+LTE devices can be used with other carriers even with the different authentication, carriers that barely have 1X cdma coverage. the conversion of the MEID to pESN is done with a different method that is of course if the DEC MEID can be retrieved, not the HEX MEID.

nakamoniel said:
OK, we all know about Verizon using lower spectrum and AT&T using upper spectrum of 700MHZ but i could never understand how HARDWARE WISE they can make a radio that would only support such a thing, I am under impression that it is the software optimized for using either upper or lower spectrum and if block the other half. I just read how flashing correct radio enabled AT&T GALAXY NOTE to be used on t-mobile, i am not an expert nor i have resources, but has anyone attempted to flash verizon radio on at&t phone or vice versa and see if phone is actually capable of running on both networks? Please explain me if there is any flow in my understanding or is it actually feasible? would be great to break monopoly of at&t and Verizon over their LTE phones even though they utilize same 700MHZ band.
Click to expand...
Click to collapse
Hardware wise it's damn easy to make a radio that doesn't support the upper/lower part of the band - just use a narrower frontend filter.
In fact, doing the opposite is hard - having wideband support without compromising the performance of your bands of primary interest is extremely difficult. Filtering out the "don't care" part of the 700 MHz band can improve RF performance in the "do care" part.
Product F(RED) said:
Certain chipsets with an integrated radio/modem support multiple bands. Like you said, in the case of the Note, XDA devs were able to flash a different modem that told the radio to tune to a different frequency that it supported. Same with the Skyrocket, and, if the T-Mobile SII had an LTE mode, that would have worked too. But not all chipsets can do multiple frequencies on one chip.
Click to expand...
Click to collapse
No, they didn't do anything to tune a different frequency. AT&T also uses AWS1700 for LTE - all they did was change modulation mode for an already supported band.

EVDO logins does not need to verify the ESN/MEID.
See http://shadowmite.com/forum/viewtopic.php?f=24&t=3319
not sure about LTE

I see thread being carried away in different direction, I understand how it used to be completely ESN based, but trust me on new LTE phones it doesnt matter, i have popped sim card into many lte devices without registering with verizon what so ever, Also both at&t and verizon phones have hardware radio built in that supports 700MHZ so that is out of question as well, Hence I would like to draw attention of everyone specially DEV's, to target the real question, is it software based solution where they have tuned radio only to support perticular upper or lower band making them carrier specific? and if so flashing verizon radio on at&t phone or at&t radio on verizon phone make it compatible with each other? IF ANYONE OUT THERE WITH RESOURCES AND knowledge of radios can try this theory, it would open infinite gates of new possibilities ( AND GIVE US ALL AN OPPORTUNITY TO SCALE UP OUR LOVE-HATE RELATIONSHIP WITH ATT-VERIZON BASTARD ).
p.s. I appreciate sharing your concerns/understanding anyways, not trying to underscore your comments, just trying to get things moving in right direction.

Thanks, its kind of answer I was looking for to verify my doubt on whether it would be possible by software tweak to enable phones work on other networks, however my speculation is that there is a huge probability that some MODELS did not bother making this changes (e.g. motorola since they do not produce phones for at&t anyways or quite oppositely HTC which makes LTE phone for both att & verizon) and simply had software tweaks in place to avoid phones on other networks, IF SO it should be as simple of radio files swap as what other guy did to samsung tab. Please correct me if i am still wrong.
Entropy512 said:
Hardware wise it's damn easy to make a radio that doesn't support the upper/lower part of the band - just use a narrower front end filter.
Click to expand...
Click to collapse

nakamoniel said:
Thanks, its kind of answer I was looking for to verify my doubt on whether it would be possible by software tweak to enable phones work on other networks, however my speculation is that there is a huge probability that some MODELS did not bother making this changes (e.g. motorola since they do not produce phones for at&t anyways or quite oppositely HTC which makes LTE phone for both att & verizon) and simply had software tweaks in place to avoid phones on other networks, IF SO it should be as simple of radio files swap as what other guy did to samsung tab. Please correct me if i am still wrong.
Click to expand...
Click to collapse
Samsung tab? Are you talking about the AT&T Galaxy Note? In that case, that was changing modulation modes in the same band. (AT&T also uses the 1700 MHz AWS band for LTE. So it's easy to just change that over to HSPA+ for T-Mo compatibility.)
I would not be surprised if Moto has narrower frontent filters, that may be part of the secret to their supposedly superior radio performance. (Rejecting unnecessary bands can greatly improve reception of the bands you care about.)