Database Users

3G on and Off

So, i have bugged folks on this forum about getting 3G to work on other carriers, and it turns out - it does work! At first i found out my settings were set to GSM only, but now i also found this weird inconsistency possibly a bug.
If i have Data Off after using 3G or GPRS for some time, when i turn it back on, phone would not connect to data service. After enabling it will simply time out.
I found that if i switch from GSM to WCDMA, and than back, 3G network would connect and work.
I don't know if it's specifically my phone, or a bug, so i'm just throwing it out there.

dialbat said:
So, i have bugged folks on this forum about getting 3G to work on other carriers, and it turns out - it does work! At first i found out my settings were set to GSM only, but now i also found this weird inconsistency possibly a bug.
If i have Data Off after using 3G or GPRS for some time, when i turn it back on, phone would not connect to data service. After enabling it will simply time out.
I found that if i switch from GSM to WCDMA, and than back, 3G network would connect and work.
I don't know if it's specifically my phone, or a bug, so i'm just throwing it out there.
Click to expand...
Click to collapse
What carrier are you getting 3G to work? I doubt its working if its anything that doesn't run on tmobiles bands..the icon will come up and stuff but your either getting edge speeds or not getting any connection. I've had this phone show me 3G with full bars and just time out.. I can eveven put in a sim with a sidekick plan or other data plan and it shows 3G but it does not work

Well, i'm overseas and i have used it on Russian carrier Beeline and carriers in two other countries. Now, i do set my connection to WCDMA only, which gives me 3G icon. When i set it to GSM only, i see GPRS icon show up.
So, it does work, i use fring, online radio, google maps. But as far as speed concerned, i have not tested it.
Just ran a speed test using Speedtest.net tool, I get 3951kbps download, and 655 upload
thats 3G

Voice AND data at the same time on the tmobile network?

I got an email while on a call without wifi. I'm in dallas. Anyone else getting data and voice now?

Has been possible since the beginning of time as long as you are on 3G

I concur. ↑
Sent from my Nexus One using XDA App

Really? I've never been able to do that until recently.
Usually when I'd start a call I'd lose the 3G icon and if I received email while in call it wouldn't show up until after I hung up.
Couldn't mess with data without wifi.
Used to do this on my cliq and G1 as well...
Odd.

Also been doing both (on TMob 3G) since February...

Any gsm phone can do that, but it is impossible for cdma

Your phone may have been set to WCDMA only up until now.

chalk that up as a win for GSM and a lose for CDMA

JCopernicus said:
Your phone may have been set to WCDMA only up until now.
Click to expand...
Click to collapse
WCDMA is 3G, it has nothing to do with CDMA

In a weak 3G signal area, the phone usually does a handover and transfers the call to the GSM network when the 3G signal falls under some threshold, and GSM doesn't support simultaneous voice and data (icon disappears while on a call)
maybe you have better 3G coverage now and your nexus doesn't need to go the GSM route

I've noticed problems with using data and voice together too. What seems to happen is that it works ok at first, but the instant you lose 3G it never comes back until the call is over, no matter how good your signal. Very frustrating when trying to use your data while on a long call.

Both AT&T and T-Mobile (as can any GSM carrier worldwide) can do voice and data at the same time as long as your phone has a "3G" connection visible while on the phone call. This has always been possible.
What you may see happen is that if you wrap your hands around the bottom of the phone during a call, the signal may drop to "E" or Edge. You can't use data and voice at the same time if your phone is on Edge.
To alleviate this, use a wired or Bluetooth headset, or hold the phone with your fingers rather than your whole palm.

Paul22000 said:
What you may see happen is that if you wrap your hands around the bottom of the phone during a call, the signal may drop to "E" or Edge. You can't use data and voice at the same time if your phone is on Edge.
Click to expand...
Click to collapse
Have you ever seen my problem where once the signal drops to Edge it will never go back to 3G? It doesn't seem like normal behavior to me but it seems to always happen when I need my data during the call. I've been stuck on multi-hour calls where my phone refused to go back to 3G almost from the beginning, and then the second I hang up the phone goes right back to a 3G signal with full bars again. Very frustrating!

pfmiller said:
I've noticed problems with using data and voice together too. What seems to happen is that it works ok at first, but the instant you lose 3G it never comes back until the call is over, no matter how good your signal. Very frustrating when trying to use your data while on a long call.
Click to expand...
Click to collapse
the ATT 3G network is not setup to do handoffs from gsm back to 3g. it currently will ONLY handoff from 3G to gsm during a call, and if you are still on your call, it will not switch back until you hang up. in the future this can be enabled both ways. tmobile apparently is setup the same way for now. so you're experience is normal until they reconfigure their network.

Actually it depends on the phone hardware. It IS possible to use GPRS and voice as well if the hardware supports it, its not only something available on 3G/UMTS/WCDMA. There is a pretty even split between class A and class B phones these days, you should look up the specs of the phone you're using.
Nearly all 3G devices allow you to use data and voice together since it isnt timeslot based and so voice and data is logically split and not time divided. This means you dont need specially designed hardware to do it, just the processing power to do it.
Class A
Can be connected to GPRS service and GSM service (voice, SMS), using both at the same time.
Class B
Can be connected to GPRS service and GSM service (voice, SMS), but using only one or the other at a given time. During GSM service (voice call or SMS), GPRS service is suspended, and then resumed automatically after the GSM service (voice call or SMS) has concluded.
Class C
Are connected to either GPRS service or GSM service (voice, SMS). Must be switched manually between one or the other service.

@kam187, thanks for that. I've been with T-Mobile since they were Voicestream, about 10 years now. And I thought I was making voice and data connections with my Nokia phone years ago, before their 3G rollout.
Here is the last phone I used before going the G1 route.
http://www.gsmarena.com/nokia_e61-1322.php

Yep E61 is on nokia's list of Class A devices:
http://wiki.forum.nokia.com/index.p...s_supporting_GPRS_Class_A_(Dual_Transfer_Mode)

[Q] Poor 3G to 2G handover

Hey there, I enjoy reading this forum but I had little to contribute with as I am an android noob. So unfortunately my first post is a question forced by the fact that something is wrong with my DHD Thank you in advance for your advices!
The problem is - when in areas with low 3G coverage the phone keeps on searching for 3G for too long instant of seamlessly switching to 2G, which often has full signal bars. This way the phone acts as if there was no signal and sends incoming calls to the voicemail even though all it has to do is to switch to 2G as soon as 3G gets too weak.
My previous phones had no problem with this. In my city the 3G quality varies from area to area but the 2G coverage is perfect almost everywhere. So I used to be sure that my phone never really disconnects from the network, it only might have dropped the 3G signal in favor of 2G while keeping the calls and everything.
I know I can disable the 3G and stick to 2G and EDGE but this way using full data capabilities of the phone turns into pain instead of pleasure.
Just to make sure and to show I did my homework, this is NOT:
- the death grip case
- a network related problem /I suppose.../
- a problem with data connection /I have never run into any problems with this/
My questions are:
- is anyone of you experiencing this?
- is there a way to force the phone to hand over the connection from 3G to 2G quicker without "blind spots"?
- does any custom ROM improve this? /I am running the latest stock HTC DHD android 2.2 with Sense/
- is there any hint that android 2.3 gingerbread should fix this issue?
Thank you, hope to find a piece of good advice here!

I`ve found this service menu and I switched the preffered network from WCDMA preferred to GSM AUTO PRL. will see if it helps.

I havent noticed any more problems since I did the switch. I think it helped. I cannot be 100% sure but I think it did the thing for me. I forgot to mention that I also switched networks mode from Auto to European but I think this has nothing to do with the issue.

fortuneman had my answer. To access the service menu on the soft phone keypad enter *#*#4636#*#* and its under Phone Information.

Switching from 2g to 3g works seamlessly. But the other way around doesn't work that well. Nothing to do with the phone. Just the net tech that has its flaws. If your in a call and switch to 2g, the call will most certainly be disconnected.
Sent from my Desire HD using XDA App

[Q] Option to use only 3G NOT HSPDA

HI all!
Right now I am using [Build][10.12.2010][NexusHD2-FRG83D V1.8 PPP+RMNET][Kernel: hastarin r8.5.3_oldcam] and that is quite ok for me.
However I havent found anywhere on that build an option to disable HDSPA speed.
What I would like is accept 3G but disable HSPDA. Now I only have a change to disable 3G totally and only get 2G. Basicly area where I live is keeping me a situation that phone is very often trying to connect HSPDA but then changes is 3G speed. It causes me time&battery drain.
I have found a solution to force phone only use 3G but that is what I wanted. 2G and 3G are ok but I want to disable HSPDA.
Anybody could help me?

Up, Up... anybody have same kind of need?

i also need same help regarding this, reason is my data plan only use 3g (umts) and not 3.5g (hsdpa)... but my android always switch 3g to hsdpa back and forth and drain battery much faster
is there any tweak/program/widget/application that can enable 3g (umts) only?
windows doenst have this problem cause in winmo i can switch the option easily (enable/disable hspa)... but android dont have this kind of thing

I have the same problem. I don't even have HSPDA where I live, yet it tries to connect, fails, and then connects to 3G. It's a very time consuming processor to wait for the phone to do this when I am just trying to load a website.

Yes.. maybe it will not drain much memory but.. who wouldn't want a fast internet..

Afaik Hsdpa uses the same radio towers (or whatever the name is) as Umts... just different software. so there should be no battery drain caused by this.

This mite help you
1. Go to your dialer
2. Dial *#*#INFO#*#*
3. Click 'Phone information'
4. Scroll down to the first dropdown selection and set according to your preference below...
For simplicity, there are two main types of cell carriers, GSM and CDMA.
The following popular data communication technology is associated with each cell carrier type:
GSM = GPRS (2g), EDGE(2g), UMTS(3g), WCDMA(3g), HSDPA(3g) {Cell Carrier examples: AT&T and T-Mobile}
CDMA = CDMA*(2/3g) EV-DO(3g) WiMax(3/4g) {Cell Carrier examples: Verizon and Sprint}
Now that the general stuff is out of the way, here's my take on the Preferred Network types:
WCDMA preferred - The GSM phone is capable of using both 2G and 3G data communication and when signal strength is low 3G is favored more.
GSM only - The GSM phone is capable of using only 2G data communication. When the 2G signal is too low you get nothing at all.
WCDMA only - The GSM phone is capable of using only 3G data communication. When the 3G signal is too low you get nothing at all.
GSM auto (PRL) - The GSM phone is capable of using both 2G and 3G data communication and when signal strength is low 2G is favored more. This one is a bit confusing to me since PRL is associated mostly with CDMA technology and not GSM technology.
CDMA auto (PRL) - The CDMA phone is capable of using both 2G and 3G data communication and when signal strength is low 2G is favored more.
CDMA only - The CDMA phone is capable of using only 2G data communication. When the 2G signal is too low you get nothing at all.
EvDo only - The CDMA phone is capable of using only 3G data communication. When the 3G signal is too low you get nothing at all.
GSM/CDMA auto (PRL) - Some phones are equipped with both GSM and CDMA capabilities. This setting appears to just have the phone attempt to stay connected to the data communication type that works the best. (Maybe the Samsung Galaxy S will take advantage of this???)
Unknown - If none of the above fit or the phone is acting weird as far as connecting to the carrier, you will see your preferred network type is set to this
Click to expand...
Click to collapse
Source http://www.google.ie/support/forum/p/android/thread?tid=6a327a95211ac789&hl=en

domenukk said:
Afaik Hsdpa uses the same radio towers (or whatever the name is) as Umts... just different software. so there should be no battery drain caused by this.
Click to expand...
Click to collapse
uhh... maybe you dont catch what us mean....
when umts change to hspda (icon change from 3g to H) then it use battery power.. in my case i use 3g (umts and not 3.5g or hspda )data plan only... but android keep searching hspda signal and THIS is when battery used the most (the process) and EVEN when my area have 3.5g covered but because i use 3g only data plan... then the back and forth process (3g<->H) will kep coming and rdrain my battery fast
so... we look for any kind of workaround so our android keep stay in 3g (umts) and not drain any unnecessary battery power searching for hspda
btw sorry for my english

agarp said:
This mite help you
1. Go to your dialer
2. Dial *#*#INFO#*#*
3. Click 'Phone information'
4. Scroll down to the first dropdown selection and set according to your preference below...
Source http://www.google.ie/support/forum/p/android/thread?tid=6a327a95211ac789&hl=en
Click to expand...
Click to collapse
i use this thing before and no luck
i use "wcdma only" as the option and android still process 3g and 3.5 back and forth, maybe android "thinks" 3g/umts and 3.5/hspda as the same?? android categorize umts and hspda as one big fat 3G network
i wonder why newer os like android doesnt have this kind of feature in winmo there is an option :
disable hspa = so hspda disabled.. AKA 2G or UMTS only
enable hspa = enabled hspda, hspa, hsupa etc.. AKA 2G, UMTS and HSPDA

try this settings
CDMA auto (PRL) - The CDMA phone is capable of using both 2G and 3G data communication and when signal strength is low 2G is favored more.

agarp said:
try this settings
CDMA auto (PRL) - The CDMA phone is capable of using both 2G and 3G data communication and when signal strength is low 2G is favored more.
Click to expand...
Click to collapse
isnt cdma auto (prl) used exclusively for cdma phones? (those phones with evdo and wimax thing) and not used for our hd2 (GSM)???

C'mon how this is impossible with newer phone software??
This feature has been in WinMo and Symbian in many years!!
It is really frustrating that almost every time my phone is trying to make HSPDA connect and then decide 3G is enough and possible. It causes some delay and sometimes also timed out errors.

agreed
my android keep going back and forth between umts 3G and hspda 3.5G like some clueless kid while 2 experienced guy (symbian & winmo) laugh at him

i know this is a old topic
i have still this issue
my phone is switching to hsdpa an back to 3g after a few seconds
when the phone is connected to my slow wifi connection everything works fine and i can use it for 3 day's
when it is connected to hsdpa my battery is empty after 15 hours and the voip connection is not working properly (i need to start a ping to some server first to keep the connection alive so i can call with voip)

I just came upon this thread, but I don't have this problem, so I can't really test it out this theory. But my thought was, what if you just went into the build.prop file and edited the ro.ril.hsxpa.category settting from ro.ril.hsxpa.category=2 to ro.ril.hsxpa.category=0. I just tested it out and it never jumped from 3g to H. My only concern is that you wouln't get the fastest speed you could be getting. Test it out and let me know though.

at this moment it is not posible to root my phone (SE Xperia pro with latest firmware)
so i am afraid we need to wait to test this
but thanks for the hint

After 2 Weeks, I Am Throwing In The Towel

I received the Samsung Focus 2 weeks ago today. After I post this I will be heading over to Amazon Wireless to make return arrangements.
I come from a Windows Mobile (Tilt 2) and I don't think I am yet ready to transition to this type of phone. I depend too much on Pocket Informant and I couldn't find any app to replace that. Actually this is not really the reason I gave up. This is the reason that kept me on the fence.
At my work I have a very poor 3G signal indoors. The signal fluctuates between 2 bars to no signal indication and sometimes switching to Edge. With the Tilt 2 I turn off 3G and that keeps the phone happy. Several times I found the Focus showing no signal (small crossed out circle at the top left). Even after I went to an area with good 3G signal the Focus did not change from its no signal status. I had to actually turn it off and back on (soft reset, I guess) to get a strong 3G signal.
Searching on Google for means to turn 3G off in the Focus showed that only a few months ago there was such an option Settings | Cellular. Apparently now it is removed.
With 3G trying desperately to hang in there instead of just giving up and letting Edge take over, this phone is useless to me 8 to 12 hours a day. The Tilt 2 had a similar issue before I tweaked it to give me the band switch. However the Tilt 2 did not get stuck in the no signal state. I wish AT&T did not remove this from settings.
So long, Focus.

Um... there's totally still an option called Cellular in Settings. Whatever, though. If you don't enjoy the phone, there's no reason for you to keep it. However, there's equally no reason for you to share this information with us, since a large part of your issue is born of ignorance of the OS (not finding a setting that is clearly there) and your lack of enjoyment of the phone should have no effect on anyone who owns one.

FishFaceMcGee said:
Um... there's totally still an option called Cellular in Settings. Whatever, though. If you don't enjoy the phone, there's no reason for you to keep it. However, there's equally no reason for you to share this information with us, since a large part of your issue is born of ignorance of the OS (not finding a setting that is clearly there) and your lack of enjoyment of the phone should have no effect on anyone who owns one.
Click to expand...
Click to collapse
Yes, the Cellular option is still there, in Settings. However, unlike screen shots or pictures I saw during my search (see this sample), I do not have the option to turn off 3G.
If your phone has it, good for you. Mine does not. Hardly a reason to call me ignorant for this though.

That's strange. My Focus appears to have better reception than my Tilt 2.
Actually, the 3G only setting is under the diagnostic menu I believe. The should have a thread in this forum on it.
Update
I checked and its under the test menu
*#32489#
Back
Back
[7] Network control
[2] Band Setting
This may help you.

Tempest790 said:
That's strange. My Focus appears to have better reception than my Tilt 2.
Click to expand...
Click to collapse
For me, side by side, the 2 phones had a similar reception. The Tilt 2 got an extra bar or 2 when I forced it to Edge. However, the Tilt 2 did not get stuck with the no signal indication.
Actually, the 3G only setting is under the diagnostic menu I believe. The should have a thread in this forum on it.
Update
I checked and its under the test menu
*#32489#
Back
Back
[7] Network control
[2] Band Setting
This may help you.
Click to expand...
Click to collapse
While at this moment I do not have the phone with me, I just looked in the PDF I downloaded from that other thread (the PDF shows [2] Band Selection) and I remember that I was in that area and when I tried to make a change I got a message saying something about the selection or option being restricted. Sorry, but I do not remember the exact words. I guess I could try again later tonight after I get home. Thank you.

Tempest790 said:
Update
I checked and its under the test menu
*#32489#
Back
Back
[7] Network control
[2] Band Setting
This may help you.
Click to expand...
Click to collapse
When I select "[2] Band Selection" the exact message is:
"RAT Selection option is restricted".

Yeah, that's what I got. I also got my phone from freaking Amazon.com and didn't work right. Had do alittle talking around but they me exchange it at the Att Wireless Store. Have you actually tried any other Samsung Focus Phones to see if its just the phone itself?

I got mine from att store, I'm using the org diagnostic app version, I get same error message.

Seed 2.0 said:
I got mine from att store, I'm using the org diagnostic app version, I get same error message.
Click to expand...
Click to collapse
I would switch phones then. The phone has to be unlocked to switch bands, even turning off 3G. That's stupid, I know. I have a Dell Venue Pro sitting here that can switch bands but that phone is VERY buggy.

Fuzzy John said:
Yes, the Cellular option is still there, in Settings. However, unlike screen shots or pictures I saw during my search (see this sample), I do not have the option to turn off 3G.
If your phone has it, good for you. Mine does not. Hardly a reason to call me ignorant for this though.
Click to expand...
Click to collapse
FWIW: 3G = "Data Connection" on the Focus' settings menu. As far as I know, 3G has nothing to do with voice calls. I suspect that the name of that switch was changed with an eye toward future data options on cell phones. I hope that helps. (Even the person who posted that picture notes that they modified the label to be "Cellular Data". You can see that in the comments area of the image/post that you listed. )

GrayWolf is correct
These are GSM phone and voice only works on 2G.. data on 3G and Edge if necessary. that is why you can talk and use the internet at the same time. You turning 3G off does nothing for your call reception what so ever. When you turn off the Celluar data you turn off both 3G and edge. Also I believe the bars are only for the voice service.

ITDRAGON said:
GrayWolf is correct
These are GSM phone and voice only works on 2G.. data on 3G and Edge if necessary. that is why you can talk and use the internet at the same time. You turning 3G off does nothing for your call reception what so ever. When you turn off the Celluar data you turn off both 3G and edge. Also I believe the bars are only for the voice service.
Click to expand...
Click to collapse
This might very well be correct, however on my Tilt 2 I have to turn off 3g in order to get full voice bars back in the location where my room is in my house. It doesn't seem to make any sense; why would the phone's 3g connection interfere w/ the 2g voice? Yet it seems like this is the case.

ITDRAGON said:
GrayWolf is correct
These are GSM phone and voice only works on 2G.. data on 3G and Edge if necessary. that is why you can talk and use the internet at the same time. You turning 3G off does nothing for your call reception what so ever. When you turn off the Celluar data you turn off both 3G and edge. Also I believe the bars are only for the voice service.
Click to expand...
Click to collapse
Sorry. I may have used the wrong terms. After all I admit I am not really familiar with all the terminology. I am more like a user. Anyway, on my Tilt 2 phone I have a switch which turn off 3G. This puts the phone in Edge mode. Gives me a lot better reception in areas where the 3G signal is flaky. True, I cannot talk and do data at the same time. Also true that my data rate is slower. But I can receive and make calls while I am in that area.

ITDRAGON said:
GrayWolf is correct
These are GSM phone and voice only works on 2G.. data on 3G and Edge if necessary. that is why you can talk and use the internet at the same time. You turning 3G off does nothing for your call reception what so ever. When you turn off the Celluar data you turn off both 3G and edge. Also I believe the bars are only for the voice service.
Click to expand...
Click to collapse
Nope. Both voice and data work on 3G if it is available. You can tell this by the fact that once your phone is on 3G, you will not encounter the annoying speaker buzz from GSM phones.
The switch in the settings are for cell data connection. If you turn it off, it turns off the data connection, 2G or 3G. There is no separate setting to turn off 3G data only (a commonly requested feature but non-existent on all AT&T phones). You will always have to access the secret menu to select your band (WCDMA or GSM).
The bars are for signal strength, not just for vocie service.

EDIT: rjohnstone
foxbat121 said:
Nope. Both voice and data work on 3G if it is available. You can tell this by the fact that once your phone is on 3G, you will not encounter the annoying speaker buzz from GSM phones.
The switch in the settings are for cell data connection. If you turn it off, it turns off the data connection, 2G or 3G. There is no separate setting to turn off 3G data only (a commonly requested feature but non-existent on all AT&T phones). You will always have to access the secret menu to select your band (WCDMA or GSM).
The bars are for signal strength, not just for vocie service.
Click to expand...
Click to collapse
<snipped my "you're wrong" message, but leaving my other data here.>
http://en.wikipedia.org/wiki/3G contains the following quote:
"The UMTS system, first offered in 2001, standardized by 3GPP, used primarily in Europe, Japan, China (however with a different radio interface) and other regions predominated by GSM 2G system infrastructure. The cell phones are typically UMTS and GSM hybrids. Several radio interfaces are offered, sharing the same infrastructure"
<snipped my "you're wrong" message, but leaving my other data here.>
http://www.phonescoop.com/phones/phone.php?p=2877
"Modes GSM 850 / 900 / 1800 / 1900
WCDMA 850 / 1900 / 2100"
Those are the GSM and 3G bands that the Samsung Focus uses. <snipped my "you're wrong" message, but leaving my other data here.>
I'm always willing to accept that I can be wrong (EDIT: and it seems that I was). I'm only human after all. If I'm the one who's somehow misunderstanding, then I would be open to having some information shared so that I can learn more about it. Would you have any links to back your claim up?

GrayWolf said:
I'm sorry to say that you've misunderstood how AT&T's network is set up. 3G + GSM = Data + Voice. Not 3G = Voice & Data.
contains the following quote:
"The UMTS system, first offered in 2001, standardized by 3GPP, used primarily in Europe, Japan, China (however with a different radio interface) and other regions predominated by GSM 2G system infrastructure. The cell phones are typically UMTS and GSM hybrids. Several radio interfaces are offered, sharing the same infrastructure"
To further back the position that our phones do not use 3G to carry voice data:
"Modes GSM 850 / 900 / 1800 / 1900
WCDMA 850 / 1900 / 2100"
Those are the GSM and 3G bands that the Samsung Focus uses. GSM for voice traffic, WCDMA (3G) for data.
I'm always willing to accept that I can be wrong. I'm only human after all. If I'm the one who's somehow misunderstanding, then I would be open to having some information shared so that I can learn more about it. Would you have any links to back your claim up?
Click to expand...
Click to collapse
AT&T sends both voice and data traffic over the 3G connection when in a 3G area.
The GSM radio only comes into play when the data connection falls back to EDGE (i.e., 3G signal is too weak or not present).
This is why your call drops when you switch from a 3G area to a GSM/EDGE area.
It's a hard hand off to the next tower.

rjohnstone said:
AT&T sends both voice and data traffic over the 3G connection when in a 3G area.
The GSM radio only comes into play when the data connection falls back to EDGE (i.e., 3G signal is too weak or not present).
This is why your call drops when you switch from a 3G area to a GSM/EDGE area.
It's a hard hand off to the next tower.
Click to expand...
Click to collapse
Thanks - would you happen to have any links that explains this in any detail?
I looked around after you mentioned it and found that I should have ran a few more keyword searches before posting. So far, the best explanation that I've found seems to be here:
"3G or Non 3G-that is the question"
http://forums.wireless.att.com/t5/G...at-is-the-question/m-p/1544262/highlight/true
The specific/relevant portion that I'm referring to is:
Yea 3G is amazing. It's the replacement for GSM. It's a completely seperate network. When in 3G at present signal in some area's might seem a bit more week than GSM because in some area's it runs on the 1900mhz frequency which has less penetration. But AT&T has plans of phasing out GSM in the future for 3G on the GSM frequency.
But 3G on the W-CDMA side handles call's and data, GSM also does handle voice and data. But the two networks are seperate. For example. If your phone is in 3G then the 3G network is handling the call and not transmitting anything to do with GSM at all. But if you travel to a non 3G area while in the call then your phone will hand off to the GSM network to continue the voice call and the call quality will get that crackly raspy phenomenom. Hope this helps!
Click to expand...
Click to collapse
Now that's another person's statement on a forum and, like rjohnstone's post, makes logical sense. I'd love to read a bit more about this, if there are any useful links out there?

GrayWolf said:
Thanks - would you happen to have any links that explains this in any detail?
I looked around after you mentioned it and found that I should have ran a few more keyword searches before posting. So far, the best explanation that I've found seems to be here:
"3G or Non 3G-that is the question"
The specific/relevant portion that I'm referring to is:
Now that's another person's statement on a forum and, like rjohnstone's post, makes logical sense. I'd love to read a bit more about this, if there are any useful links out there?
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Graywolf,
My friend is a tower manager for T-Mobile.
He helped setup the initial GSM/EDGE network for Cingular back when they leased tower time from T-Mobile while they were making the transition from TDMA devices from the old AT&T network.
He explained how the call handlers worked and how the air interface works when handing off from UMTS/HSPA over to the GSM/EDGE network.
All of AT&T's handsets are programmed to use either GSM/EDGE or UMTS/HSPA, not both at the same time.
The point is, a handset can't have a GSM voice call and an HSPA data session occurring at the same time. The radios are not configured to allow it.
Many towers run both GSM/EDGE radios and UMTS/HSPA/HSPA+ radios.
Mainly to support legacy devices.
You will also notice that the old network is still there when you turn of the 3G radio in an iPhone or any other handset that permits it.
Yes, AT&T is working to decommission the older GSM/EDGE towers all together to recover the 850Mhz frequencies for use with HSPA+. This will give them better building penetration in large metropolitan areas.
Right now, AT&T does use the 1900MHz band for HSPA, and as the residence of NY will tell you, it sucks at going through walls.
You will have to do some digging for old AT&T press releases, but the info is out there.

Gotta give credit where it's due. I appreciate the technical detail combined with layman phrasing. I'll do more digging later but you've given me a nice high-level view of things. I did have a suspicion that my understanding was flawed somehow. Thanks for taking the time to share, rjohnstone!

Yep your right I typed it wrong.. voice and data both work on 2G and 3G, but I know I'm in a 3G area only and when I turn data off 3G goes out. Now that doesn't mean I'm only making or recieving calls on the 2G band. It just mean 3G data is off. So if you want to turn off 3G all together, I don't see it on these phones yet. When I turn the celluar data back on, the 3G symbol comes back on, because it would be pretty dumb for the 3G to be controlled by turning data on and off.