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I saw the T-mobile ads for their $50/month unlimited talk/text and 500MB data plan so I hooked up my AT&T-unlocked iPhone 3GS on T-Mobile in the Orlando area in July.  As I traveled around this metro area where AT&T was always 4-5 bars, I noticed that T-Mobile was also 4-5 bars, so far so good.


BUT, BUT, BUT when I went home and tried to use my iPhone in a 2-3 bar area, unfortunately, it would ping-pong from 3 bars to 2 bars to 1 bar and then drop off the 3G network and attach to the Edge network and then cycle back to the 3G network again. It did this constantly at home and in any 2-3 bar area which most of the metro area happens to be once off the interstate corridor.


When the iPhone ping-ponged from 3G to Edge to 3G, etc., it always froze up inoperative & unresponsive to its buttons and/or dropped calls in progress and/or lost all service and went "searching". This lasted anywhere from 20 seconds to several minutes!  On 3 occasions, the iPhone froze indefinitely until the confusion timed out about 5-7 minutes later!


My friend's iPhone 4S did the same exact thing when the SIM card was moved and the experiment repeated. So, it wasn't an iPhone problem after all.  What was it???


T-Mobile doesn't tell you this before you hook up an iPhone with them BUT, no AT&T iPhone has ever had built into it T-Mobile's CDMA channel 1700/2100 which T-Mobile uses for it's primary 3G send/receive channel.  Even though it's a GSM carrier, T-Mobile uses their CDMA channel for most all 3G service, which is the iPhone's favored method of network communication.  The iPhone does not have these channels so it cannot use T-Mobile's native 3G service.  To get around this, T-Mobile uses their excess Edge network channel capacity (if they have any) to communicate with the iPhone at 3G speed.  BUT, whenever T-Mobile has Edge network congestion, they boot the iPhone off of 3G service on those Edge channels and give it to their Edge customers.  The iPhone then tries to connect via the Edge network and that's when the freeze-ups and dropped calls become a BIG problem - the iPhone is almost worthless on the Edge network - it chokes, freezes, drops calls in the attempted switchover, etc.


My experience over 5-6 weeks proved to me that the unlocked AT&T iPhones tested on T-Mobile were functionally

unsatisfactory at best and completely worthless when they froze up and lost the network as they went "searching".  The ONLY solution is to buy an Apple UNLOCKED iPhone 5, 5C or 5S (they sell a T-Mobile version which HAS the missing channel 1700/2100) and use that on T-Mobile's network in order to be able to use T-Mobile's native 3G network without the ping-ponging to Edge and back.


SO, BEFORE YOU WASTE YOUR TIME LIKE I DID and move your AT&T-unlocked iPhone to T-Mobile, reconsider what you will be up against after you do it - You'll experience undependable, problematic service or no service whatsoever in most cases. This is well-documented in T-Mobile's customer forums and there is really no solution for it except to buy the Apple/T-Mobile iPhone 5 or newer - NO previous iPhone 3GS, 4 or 4S has ever had that 1700/2100 channel built into it - Only the Apple Unlocked iPhone 5 or Apple/T-Mobile iPhone 5 has it.


I'm back with AT&T for good now!  AT&T's outstanding customer service and better network coverage can't be beat in this area - But, I pay about 25% more for it as compared to what T-Mobile offered.  I hope sharing this will help someone else avoid the dilemma I went through.


Message 1 of 9
ACE - Professor


Wait wait wait. There seems to be some confusion here. While you are correct that the iPhone 3GS and iPhone 4S don't perform too well on the T-Mobile, and the reason being it lacks the 1700/2100 bands, the real reason your devices didn't perform too well is because it operated on their refarmed 1900MHz band, which doesn't penetrate indoors to well.

However if you had a phone like say the iPhone 5 which does now have the AWS band, it would perform a bit better on their network. AT&T is definitely the superior network, but just had to clear that up.
~Sunshine Smiley Happy
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 2 of 9


I understand your frustration.  I have the exact same problem.  When mine is switching between 4G E ect my phone doesn't ring on my phone or go to voicemail.  It continues to ring on the other person's phone but never gets in contact with mine.  It is a lost call.  I never even know the person called.  No telling how many important calls I have missed.


I did associate my phone with google voice yesterday.  It picked up several calls that did not appear on my phone.  That may help you some.  It does make you wonder why you are paying for the service through the carrier though. 


There is a difference between your problem and mine though.  I am with ATT.  ATT coverage may be superior to T-Mobile but I'm not so sure that's true with the other carriers.  I've noticed that the coverage map, at least for my area, is far better with Verizon.  

Message 3 of 9


Your comments are only partially correct....


1.  Only SOME AT&T iPhone 5's have the missing T-Mobile CDMA channel 1700/2100....those made AFTER late-April, 2013.  Good Luck trying to figure out whether yours has or doesn't have the missing channel you refer to.  The vast majority of AT&T iPhones sold DO NOT have the channel and never will if they are ever unlocked and moved to T-Mobile. That's one reason I posted my experience.


2.  Whether or not T-Mobile's CDMA channel penetrates buildings as well as GSM 1900 is all theoretical outside of a 5-bar urban corridor (which T-Mobile serves well).  My tests were done over a 45 day period in the metro and suburbs, outdoors and indoors, in wood frame and some combination-construction buildings, both commercial and residential and, most importantly, in passenger vehicles while driving in 2-3 bar T-Mobile service areas.  The ping-ponging occurs even when standing still out in the open!  My experience and tests reflect normal cell phone use in this metro area - not some theoretical or philosophical argument as to which type of electronic frequency penetrates buildings better.  The reason I posted my results is because, in NORMAL circumstances, any unlocked AT&T iPhone 5 (most all), ALL 4s, ALL 4 and ALL 3GS, operated on T-Mobile's network will ALWAYS SUFFER from intermittent or no service whereby, if operated on the AT&T network, they perform completely satisfactorily.  Just beware of what IS, not what MAY be.


3.  Again, the ONLY bulletproof solution to getting satisfactory iPhone service on the T-Mobile network is to buy NEW equipment directly from Apple (unlocked) or T-Mobile which has the missing 1700/2100 channel built into it.  Moving unlocked AT&T iPhones to T-Mobile will ALWAYS result in COMPLETELY unsatisfactory T-Mobile service.


Now, if you really want to get theoretical, tell me in another thread why AT&T charges me an extra $20 per month to "provision" my iPhone on my $50 per month 300MB Mobile Share plan making it $70 per month, while T-Mobile doesn't charge for that on their equivalent (superior) $50 per month unlimited talk & text & 500MB data plan?





Message 4 of 9
ACE - Professor


You are correct in the fact that only iPhones made April 2013 and beyond hold the AWS band. It's really easy to tell if it holds the bands. It's on the box on the back, it should list as 850/900/AWS (1700/2100) etc. if it doesn't have it listed (which is unlikely today), then it's not a iPhone that can be used to its full potential on T-Mobile.

The problem with the bands T-Mobile uses is that it does not penetrate the walls very well depending on where you are/live. The lower the band is, the better it penetrates through walls. AT&T uses 850MHz for 3G and 4G HSPA+ which is why it's much more reliable. Would be similar results with let's say.. Verizon.

I can't honestly tell you why they charge an extra $20 to "provision" a phone, but what I do know is they charge that for Mobile Share plans. You pay because you know the network is superior and reliable. Yes T-Mobile charges less for their plans but remember that AT&T covers much more areas compared to T-Mobile.. For example more urban areas, much more major highways etc.

Not saying T-Mobile is horrible at all, it does work for some people, but it ultimately depends on how much your willing to pay to use a cell phone. For some people, they might think AT&T's prices are expensive but love the network. For T-Mobile, people love the prices but may or may not like the network.
~Sunshine Smiley Happy
*The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
Message 5 of 9


Here is an interesting article.

I can't find it at the moment but there was a comparison of LTE speeds and AT&T was a clear winner because you use data it 's  important or you did not need a smart phone afterall.

Found it.

Message 6 of 9


LTE Speeds.PNG

Message 7 of 9


That rootmetrics article you posted is interesting. It shows that ATT is slightly faster than Verizon but that you are more likely to actually connect to LTE through Verizon. In the markets they tested LTE was available in all 77 markets for Verizon. ATT was only in 47 of the 77.


“Verizon’s LTE footprint is its biggest and most impressive advantage. We found Verizon’s LTE network in all 77 markets that we tested. Compared to the 135 markets that AT&T labels as LTE-enabled, Verizon proclaims LTE coverage in over 475 markets across the nation. If broad LTE coverage is your top concern, Verizon currently offers a clear advantage. That lead could shrink in 2013, as Verizon reaches a saturation point and AT&T continues its aggressive rollout. For the moment, though, Verizon is the hands-down leader when comparing LTE footprints.”

Message 8 of 9


Just goes to show you that the grass isn't always greener on the other side. I don't blame you for wanting to save a little green, though.

As far as LTE goes, I would personally rather have more reliable coverage in most areas than faster speeds in a few select areas. AT&T should diligently keep adding LTE service to more markets across the nation.

Cat Happy Remember that Wild Banchi... 1993-2010 Cat Happy

Message 9 of 9
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