I bought one of these phones, rooted it, unlocked it, and installed CM9. I love the phone and OS, but I cannot get the 3G/4G to work on AT&T. Any ideas?
Yeah. The data network is incompatible. Different frequency.
Sent from my SGH-T769 using xda premium
Yeah I think all you can get is 2G (edge) on AT&T with the blaze.
I can say from first hand experience that the blaze works great with AT&T's 3g service. I bought this phone last week, unlocked it, and swapped in the sim from my old Aria and have been using it with CM10 ever since. Data speeds are around 3 to 6 Mb/s down and 1 Mb/s up, and voice and text messaging works fine.
For a more technical answer, AT&T uses the 850 mhz and 1900 mhz frequencies for UMTS (3g), and T-mobile uses 1700 mhz and 2100 mhz frequencies. The blaze supports UMTS on all of these frequencies so there are no technical roadblocks to using this phone with AT&T. http://www.phonearena.com/phones/Samsung-Galaxy-S-Blaze-4G_id6824
As for your problem of not getting 3g working, I had similar issues when first switching the sim card (especially on the stock rom). Check that your APN matches the one your old phone was using. On the stock rom, the phone did not auto detect the correct APN and this caused the 3g to not work. CM10 detected the correct APN right away though. Also, try turning data off and on or even rebooting the phone once you've checked your network settings.
I sold my other phone and no longer have it. Please confirm your APN settings, and how do I change them?
The blaze has all the frequencies necessary for it to do HSPA (3G/4G) on AT&T's networks.
You'll likely want to change the APN. On CM9/10, go to Settings -> Wireless & Networks + More... -> Mobile Network Settings -> Access Point Names.
I was careful in selecting this specific phone because of its compatibility with AT&T HSPA bands. I have tried the suggested tweaks to the APN settings within both CM9 and CM10, but I still get no visual notification that the phone is operating in 3G or 4G mode. The areas in which I have used the phone consistently provided 3G and/or 4G coverage consistently with my prior BlackBerry 9860.
Any additional tips/tricks would certainly be appreciated. I know this phone is capable of so much more than it's providing me at this point.
nellans57 said:
I was careful in selecting this specific phone because of its compatibility with AT&T HSPA bands. I have tried the suggested tweaks to the APN settings within both CM9 and CM10, but I still get no visual notification that the phone is operating in 3G or 4G mode. The areas in which I have used the phone consistently provided 3G and/or 4G coverage consistently with my prior BlackBerry 9860.
Any additional tips/tricks would certainly be appreciated. I know this phone is capable of so much more than it's providing me at this point.
Click to expand...
Click to collapse
have you tried running a speed test to see if maybe it's just that the icon isn't coming up?
That is why it was called the "Merger Proof Phone"
Related
I'm currently running eagles blood 2.3.5 custom rom and my data is wacky. Mostly my data will say 1x which is cdma technology, which I usually get decent speeds with. But now I get H appearing which is HSPA. Is there anyway to keep just the hspa. Apps like Netflix don't work on CDMA and its very annoying. So what's the deal? Is my data wacky or do I need to change my preferred network? It's currently set to WCDMA preferred.
Sent from my LG-P999 using XDA App
I think you mean GSM, not CDMA.
Go to your Settings, Wireless Networks, Mobile Networks, Network Mode, and change it from GSM/WCDMA to WCDMA only. Now if you are anywhere where there is a 3G/4G signal, you will get it instead of the phone switching to a higher 2G signal automatically. However if you are in a 2G area, you will need to switch back to GSM/WCDMA.
no hes right its cdma technology, i think it might be simple, if u go into ur access point simple is probably checked off u need it to be tmobile and hit search networks even if it says error keep doing it until u get the option to choose tmobile , same thing was happening to me on fauxs rom lol i think verizon uses that too it looks like this rite....1X
Iwent into the access point settings and its checked off with T-Mobile. No dice, still switching back and forth. I also live in an aera that has hspa+. Its weird because on my old mytouch slide it was able to just use the hspa network no problem. With this switching its severely draining my battery. People said they can get 24hrs with there phone on this rom, I got 6 today. Thanks for the replies guys, I really appreciate it.
UPDATE: Wi-fi calling works fine which is confusing that I'm still getting 1x when my network settings are all set to t-mobile
Sent from my LG-P999 using XDA App
So i downloaded Elixir and heres the deal:
Eaglesblood:
1X uses CDMA
E uses GSM
H uses HSPA
Stock:
2g uses GSM
4g uses HSDPA
is there anyway to fix the eaglesblood rom so it uses just the 2 like stock does?
Hello,
So i've got this nicely unlocked, shiny, G2x. (Running MIUI right now, please don't judge me) Anyways, I'm in Morocco, and am trying to use Maroc Telecom (IAM) which has 3g data (their site even claims HSPA+) and these are the frequencys they use:
GSM 900 / GSM 1800 / UMTS 2100
And copy pasted from the T-Mobile website, the G2x uses:
Quad band GSM (850/900/1800/1900 MHz), Dual band UMTS (1700/2100 MHZ Bands 1 & 4)
To me that looks compatible. Trouble is, i'm getting no data whatsoever, not even 2g, in an area that I know should have at least 3g. I've signed up for the plan correctly, I'm sure of that. And my G2x automatically picked up the APN settings when I first turned it on (and I verified that they are correct) but still not a hint of internet access. This is driving me crazy!! any hints would be greatly appreciated.
Just guessing, but does it think you're roaming. Maybe try enabling data roaming to see if it recognizes the data then.
fiffer1 said:
Just guessing, but does it think you're roaming. Maybe try enabling data roaming to see if it recognizes the data then.
Click to expand...
Click to collapse
It wouldn't be roaming if he bought a sim for that system as he says. Probably APN has a typo or not selected. Have to push radio button so it has a green dot to enable the APN. If that doesn't work then contact carrier to reset data on the account. I have had to do that in the past here in Thailand. Have you also tried turning the phone off and on, or doing airplane mode. Sometimes that is needed once.
Thanks for the responses!
Unfortunately, i've tried and double tried all those things, except getting the carrier to reset the data plan. I'll do that next. Now I just have to get through a bunch of menus in French & Arabic
Are you running Market Enabler. It can screw you up royally if you change sim and it was set to fake at boot. I had that on a Nexus One and had to factory reset the phone to get data working again when I changed sim.
Thanks for the advice. I don't think i'm faking my sim - unless that's something that comes with CM07 and I just don't know about it. Also I tried it on stock before flashing with no different result, so i'm pretty sure that's not it. Went to the office of Maroc Telecom, who replaced my sim (but still no luck) and an INWI sim which i'd previously been able to get 2g coverage on now gives me nothing. It is the weirdest thing and I feel stuck. Has anyone actually gotten a g2x to work on any other network?? is there some sort of Tmobile lock which is preventing me because i'm not using a tmobile sim? (And i'm not talking about the phone being 'locked', obviously i've gotten it unlocked, and can make calls just fine, and did have that short spell of 2g data on INWI) Anyways, i'm about ready to throw this very expensive phone out the window, because what is a smartphone without data?? Thanks anyways for your advice.
same, problem.
How can I solve it?
Maybe try to use other broadband?
I use my G2X in Thailand on TOT3G with no problems. They run 3G on Band 1 (2100/1900). Figure out what band it is. There about fifteen different 3G bands in use. Most people don't realize it but 3G radios use two frequency spectrums at the same time. There is an uplink and downlink. For example 2100 Band 1 uses 2100Mhz downlink and a 1900Mhz uplink. Band 4 is 1700Mhz uplink and 2100Mhz downlink. So the 3G radio in the G2X also transmits on 1900Mhz. But the 1900 Band 2 uses 1800Mhz as an uplink, which the 3G radio in the G2X doesn't support. Most companies that say they are on 2100Mhz are referring to Band 1. If they are running Band 1 the G2X definitely supports it. If you have sim unlocked the phone there is nothing preventing you from getting 3G reception on any carrier in the world.
Download "Network" (https://market.android.com/details?id=de.mangelow.network&feature=search_result) from the Android Market and run it. Scroll down to where it says what type of connection you want and make sure "WCDMA preferred" is selected. If the phone somehow got set to "2G only" you will never get 3G reception until you change it. That happened to me once on a Nexus One and took me a while to figure it out.
CM7 and some other custom roms are known to be having connectivity issues. I suggest you flash back to stock and make sure your apn is correct. If your apn is wrong in any way, the connection will be refused by the cell system.
answer to problem with 3G
engadget[dot]com/2011/04/27/t-mobile-g2x-lacks-quadband-hspa-shatters-dreams/
So, I have working 2G, and 3G(only data, calls are not working)
Rom: WeaponG2x.
Have you tried hard reset (press and hold vol^ and power) till it restarts..
Sent from my LG-P999 using xda premium
MisfitX said:
Have you tried hard reset (press and hold vol^ and power) till it restarts..
Sent from my LG-P999 using xda premium
Click to expand...
Click to collapse
For the what?
Herro! first time poster, long time lurker! i searched around, and couldn't really find a similar problem.
I got an HTC one S from Fido, unlocked it, and i've been trying to use it on Bell. I tried several different APN's until one finally worked...but only EDGE speeds! It's also draining my battery extremely quickly. also, when i put my bell sim card inside, preferred network mode changes to WCDMA instead of HSPA (like on the fido sim).
why is this happening? i was told a fido phone would work on bell with no problem. why no 4g speeds?
thank you and i appreciate the responses in advance
HSPA uses WCDMA, so that makes no sense... Under preferred network you should have WCDMA only, 2G only, or WCDMA preferred if I recall correctly as I'm not on stock HTC rom atm so can't check. Are you getting an "E" signal indicator or are you just getting a slow connection? What does it say under About phone>Status>Mobile Network Type?
Set it to Auto mode in the network settings.
frdd said:
HSPA uses WCDMA, so that makes no sense... Under preferred network you should have WCDMA only, 2G only, or WCDMA preferred if I recall correctly as I'm not on stock HTC rom atm so can't check. Are you getting an "E" signal indicator or are you just getting a slow connection? What does it say under About phone>Status>Mobile Network Type?
Click to expand...
Click to collapse
yeah, all the tech support i've talked to said it makes no sense either . i get the same outcome whether i put it on WCDMA only or GSM/WCDMA auto. when i do the speed test, it always comes out under 1 mb/s. it actually has the 4G symbol up, but the speed isn't there.
mhmm, it switches between UMTS and HSDPA.
If you have UMTS and HSPDA under status its working, and those are also what connection you're really on. If you always have a 4g icon on status bar it seems like your carrier has modded the software like T-Mobile USA does so it always shows 4g no matter what's up in the real world.
Maybe you're not in a good location and that's why you get slow data. Also I have no idea how Canadian carriers work but I'd guess if you're connected to a 850 MHz cell you'll get worse speeds than on a 1700/1900 one. Don't you guys have insane data caps everywhere, perhaps you hit yours when speedtesting?
did you try a new sim from bell
I thought I can connect my 4GS onto the other UMTS network, but its max was HSDPA:9 (HSDPA:8 in JB).
Other phone such as Photon Q didn't have problem in connecting with HSPA+:15
Do I have to manually enable something? I believe this phone's potential is better than this
My carrier is using 2100MHz band, and my baseband ROM is a new one.
Is this info relevant : ?
http://forum.xda-developers.com/showthread.php?t=1914122 [ Enable North American UMTS/HSPA bands (3G data on AT&T)]
palmwangja said:
My carrier is using 2100MHz band, and my baseband ROM is a new one.
Is this info relevant : ?
http://forum.xda-developers.com/showthread.php?t=1914122 [ Enable North American UMTS/HSPA bands (3G data on AT&T)]
Click to expand...
Click to collapse
If your carrier is using the 2100MHz frequency, this phone should have no problem using HSPA+ with it. When I travel to China, I use a China Unicom SIM in my MT4GS which enables my phone to use their 2100MHz HSPA+ network without any problem. Back at home in US, I use T-Mobile SIM.
Fuzi0719 said:
If your carrier is using the 2100MHz frequency, this phone should have no problem using HSPA+ with it. When I travel to China, I use a China Unicom SIM in my MT4GS which enables my phone to use their 2100MHz HSPA+ network without any problem. Back at home in US, I use T-Mobile SIM.
Click to expand...
Click to collapse
Thanks, I don't know what causes this...
So, you are seeing H+ (HSPAP:15) right? All I can see with various ROMs are only 3G and H....
Do speed tests, symbols don't always mean what they say after all
Sent from my Nexus 4 using xda premium
just tested: only around 3Mbps whereas other hspa+ phone got 9Mbps...
Is there any hidden menu to tick this on?
palmwangja said:
Thanks, I don't know what causes this...
So, you are seeing H+ (HSPAP:15) right? All I can see with various ROMs are only 3G and H....
Click to expand...
Click to collapse
The stock ROMs are configured by HTC/T-Mobile to display 4G when it has a HSPA+ connection. Other ROMs, however, will display 3G or H (depending on the ROM) for HSPA+. So, if you see 3G, H, or 4G, they are all HSPA+ connections. This phone operates data in the G (GPRS), E (2G or EDGE), and 4G/3G/H (HSPA+) modes. Depending on the carrier, it can perform up to 14Mbps HSPA+ but of course, you would rarely see that fast in the real world. It does not operate at the 21+ or 42+ levels of HSPA+.
I'm on a stock-based ROM (Miktouch), when I'm home on T-Mobile, I see 4G. Also, when I'm in China and connected to China Unicom, I see 4G.
I've never seen "H" on this phone, it always shown 3G or 4G (using stock ROM, just de-junked and rooted by myself)
IIRC speed test results, I had best down speed exceeding 14+Mbps on Wind in Vancouver and Toronto areas, but in US it almost always was 3G only (but then I was usually outside any large cities).
Fuzi0719 said:
The stock ROMs are configured by HTC/T-Mobile to display 4G when it has a HSPA+ connection. Other ROMs, however, will display 3G or H (depending on the ROM) for HSPA+. So, if you see 3G, H, or 4G, they are all HSPA+ connections. This phone operates data in the G (GPRS), E (2G or EDGE), and 4G/3G/H (HSPA+) modes. Depending on the carrier, it can perform up to 14Mbps HSPA+ but of course, you would rarely see that fast in the real world. It does not operate at the 21+ or 42+ levels of HSPA+.
I'm on a stock-based ROM (Miktouch), when I'm home on T-Mobile, I see 4G. Also, when I'm in China and connected to China Unicom, I see 4G.
Click to expand...
Click to collapse
Thanks for the input, if you are using non-stock rom, still would you let me know what the following says in the most normal case:
setting - phone - status - mobile network type.
In my case, it's HSDPA:9, which seems obviously non-HSPA. Other phone shows HSPA+:15 or HSPAP:15.
Am I missing something, or HSDPA:9 can be also considered as a decent HSPA+ ?
I'm kinda downshifting toward MT4GS recently as I love its small form factor, but somewhat at a loss due to this limitation, thanks.
Please help! Network issues - will *not* connect at all anymore!
I just bought this phone (XT1557) just over a week ago. I unlocked it and installed TWRP then made a backup. Then I installed AOSP Extended and was enjoying learning about it and using the phone. I'm using H20 Wireless (they use AT&T network). Everything seemed to be great for about a week and I was very happy with my new phone. However, just yesterday, while traveling in the US and using the phone (for maps/navigation, gasbuddy, facebook, etc. - it was also charging from a car charger at the same time) we hit a patchy spot in the signal and I couldn't get the network to reconnect. After a few minutes (still traveling) for a split second the network icon flashed as having a decent signal, but then it went off again and *NEVER CAME BACK*! Nothing I've done since then has been able to get the network to come back on my phone.
Here's what I've tried:
* toggling airplane mode, toggling preferred 4G/LTE, or 3G, or 2G
* Reboot;
* safe mode;
* tried sim in the other sim card slot
* tried another sim in my phone that was currently working at the time in Moto G 2nd gen, in both sim slots - still not working in my phone; tried my sim in that phone and it's working in that phone (so not a sim card problem)
* tried *#*#4636#*#* - still shows "emergency calls only" and the signal strength does fluctuate depending on where I move around (see screenshots), tried bunch of different radio bands, tried turning off and on radio power, tried changing preffered network type (to lots of different ones)
* tried dirty flashing AEX again and newest GApps
* tried clean flashing AEX and newest GApps
* tried clean flashing Lineage OS 14.1 and newest GApps.
* flashed only the original modem firmware from MM stock rom (provided here at xda)
* restored my nandroid backup to stock rom (6.0.1)
NONE of these things have worked! PLEASE help! Is there any way I can test this to see if it's a hardware issue? (Though it seems strange for hardware to fail after just 1 week... and there's no warranty since I unlocked it, but I bought it new on ebay anyway, so no warranty.)
Any help you can give will be so appreciated. Nothing else on the phone seems to have a problem (wifi, etc., all seem to be working). The phone didn't even act weird when the network stopped working -that was the only thing. Everything else on the phone still acted like normal without even a reboot. If you've ever even heard of this happening, please let me know. I can't find any other info on what to do on the internet and I've searched all over. If you can help me (or even try), I'll give you so many thanks, as many as it lets me give on here! Thank you for even considering helping me - I really want this to work!
I don't know for sure if this is the case, but here is a possibility...
There is no 2G (GSM) service on H2O/AT&T, period, it was shutdown in December 2016.
For 3G AT&T uses 850Mhz & 1900Mhz HSPA(+), but it varies which one based on licensing and network saturation, among other things... Not everywhere has both (in fact, both only appear in select high-penetration markets)... the XT1557 supports HSDPA 850/900/2100, note that 1900Mhz is NOT a supported frequency, yet it is quite common in AT&T's network... It is a possibility that you left an area with 850Mhz service, and entered an area with 1900Mhz service and now have no service, literally. The service is there for AT&T/H2O, but your phone doesn't support the frequency in that area.
LTE bands support by the XT1557 are LTE band 1(2100), 3(1800), 7(2600), 8(900), 28(700), 40(2300), but none of those are compatible with AT&T.
It is entirely possible that you just don't have service, because there is NO service your phone is capable of getting because either that frequency isn't available or it's used by another carrier in that area (and H2O has no roaming from AT&T's core network to partner networks like AT&T post-paid service).
Just a possibility... but basically you have a device that only supports a portion of the network you are trying to use.
acejavelin said:
I don't know for sure if this is the case, but here is a possibility...
There is no 2G (GSM) service on H2O/AT&T, period, it was shutdown in December 2016.
For 3G AT&T uses 850Mhz & 1900Mhz HSPA(+), but it varies which one based on licensing and network saturation, among other things... Not everywhere has both (in fact, both only appear in select high-penetration markets)... the XT1557 supports HSDPA 850/900/2100, note that 1900Mhz is NOT a supported frequency, yet it is quite common in AT&T's network... It is a possibility that you left an area with 850Mhz service, and entered an area with 1900Mhz service and now have no service, literally. The service is there for AT&T/H2O, but your phone doesn't support the frequency in that area.
LTE bands support by the XT1557 are LTE band 1(2100), 3(1800), 7(2600), 8(900), 28(700), 40(2300), but none of those are compatible with AT&T.
It is entirely possible that you just don't have service, because there is NO service your phone is capable of getting because either that frequency isn't available or it's used by another carrier in that area (and H2O has no roaming from AT&T's core network to partner networks like AT&T post-paid service).
Just a possibility... but basically you have a device that only supports a portion of the network you are trying to use.
Click to expand...
Click to collapse
Wow, this info could be SOOO helpful! I know this is only a possibility, but it gives me a glimmer of hope when I thought the phone was doomed/broken somehow. I did know my phone was only partially supported (like I knew I probably couldn't get LTE in the US), but I didn't know what all that meant in terms of the other bands. I bought the phone for primary use in Madagascar (which my phone appears to cover all the bands used in Madagascar) but I won't be back there until September, so I'm using the phone in the US in the meantime.
Even though I considered my phone/SIM might not be compatible with the local network, I figured that couldn't be the case since there was clearly a signal in the Moto G2 XT1068 (Titan). However, with what you explained, that might explain some other anomalies. My Titan is also a phone made for international use (where I've used it for years in Madagascar and South Africa and it works great), but when traveling here in the US, I've noticed some anomalies that your explanation might explain (assuming the Titan might also have limited frequencies in use by AT&T/H2O in various parts of the US). For example, in Alaska,there was a time when in southern Alaska (inside passage) my Titan worked great, voice/data, everything (even in some way out of the way places)... then later in central Alaska my wife's phone (an old AT&T phone with a post-paid AT&T sim) got a data signal, and my Titan got a voice signal but no data. It was strange. Didn't work in some airports along the way either (I don't remember which ones, maybe Chicago). It wasn't until we were back in St Louis that the data started working on my Titan right away again, no problem. I figured it was some strange glitch of the OS (CM 13.1) in how it searched/recognized the local network. But maybe it was a limit in the phone's available bands in those regions of the US?
Then again, after I got the new XT1557 (just over a week ago), I transferred my wife's AT&T postpaid SIM to my old titan (XT1068). It was working great, but I never thought to check her mobile data away from wifi (just got busy and never thought to check). At the same time we hit the spotty network connection while travelling 2 days ago (northeastern Missouri, the network was spotty and cutting out on both our phones), that was when my signal went out for good and I saw that hers (AT&T postpaid but now in a Titan XT1068) didn't have a data signal when her network/voice signal came back. That made it very difficult to navigate, so we stopped and refreshed our maps at public wifi. I thought maybe I just needed to update the APN with AT&T, but when I manually input the info they gave me, it still didn't give me a data signal (on the Titan). Now we're in the Des Moines, Iowa area and I'm experiencing everything I've written about with my phone having never recovered a network signal. However, the one anomaly is that, even when I put my H20 sim back in my Titan XT1068 (which I thought was always working in the past, minus that anomaly from the Alaska trip) it gets a good voice signal but still no data signal, just like my wife's prepaid AT&T never got a data signal (that I could see), and even though I know which APN settings to use for H20. I've similarly been beating my head in over the titan's lack of data signal since I refreshed the OS (now on Lineage OS 13.1) since it means we have 2 phones with us on this trip, neither able to get data since leaving northeastern Missouri and mine even worse getting no voice signal at all.
But maybe it means my Titan XT1068 also has limited bands that aren't covered by AT&T/H20's data here even though it's covered by their voice?
The info you've provided so far is excellent. Can you provide similar info about the XT1068's available bands? (I'm not sure where to find all that - I found the original info about XT1557 in the wikipedia page, but Moto G 2nd gen doesn't seem to list the bands specifically. I also don't know where to look for AT&T's specific bands and/or coverage map that might indicate where they have coverage with each band.) If you can provide any of that info it would be so great! But for now, you've extended my hope for my phone. We'll be in Minneapolis area in a few days, so maybe I can try again there. Then we'll be back in St Louis area (where it was working great previously) in just over a week. So at least I'll hold out my hope until then and maybe I'll discover this just isn't the best travel phone for northern US (or other parts of the US). Still, I can't thank you enough for the hope you've given me, even if it is *just* a possibility. It does seem to explain the circumstances.
Sorry for the long story! I just wrote to show that your explanation might really fit well! Your info was so helpful! Please follow-up to tell me if you think the extra info I gave confirms what you wrote. Please also help me find a coverage map for AT&T where I can see where in the US they use specific frequencies. If you can do that for me. Thanks again for being so helpful and explanatory!
@madagascaradam Search by model and then and find the GSMArena page for the device, under the Network section click Expand...
2G bands GSM 850 / 900 / 1800 / 1900 - SIM 1 & SIM 2
3G bands HSDPA 850 / 900 / 1700 / 1900 / 2100
Speed HSPA 21.1/5.76 Mbps
GPRS Yes
EDGE Yes
Click to expand...
Click to collapse
So the Moto G2 you have supports the proper HSPA (but hot HSPA+) bands for all AT&T's 3G frequencies.
Remember that prior to December of last year, likely when you were referencing your Alaska trip, there was AT&T 2G/Edge service nationwide but that has since been shutdown and within the next 2-3 years all 2G GSM and CDMA service in the US will be shutdown from all carriers.
And I used H2O for quite a while, use this APN (there are lots of older settings out there, they don't work quite right, but this is current as of a month or so ago at least):
Name: H2O Wireless
APN: prodata
MMSC: http://mmsc.mobile.att.net
MMS Proxy: proxy.mobile.att.net
MMS Port: 80
MCC: 310
MCN: 410
Authentication Type: Not set
APN type: default,mms,supl,hipri,fota
APN Protocol: IPv4
APN roaming protocol: IPv4
everything else blank, not set or none.
@acejavelin You were totally right! In Minneapolis area I usually had a signal, but not much outside the area. In Iowa no signal at all. But once I got back towards central Missouri the signal has been working great again. So obviously ATT has some regions that use 850 (like in the south) and others further up north that seem to only use 1900 which isn't supported by my phone (XT1557). So, that's not super great for using my phone in the US, but at least I know it's not a problem with my phone.
I also found this map (older, from 2008) which shows where AT&T had 850 MHz frequency and where it had 1900 MHz frequency. It roughly corresponds to my experiences so I definitely think it all adds up. http://www.cellularmaps.com/att_850_1900.shtml
Again, thanks so much for your help!