Slow data while on call (AT&T - iPhone 5)

My problem is almost exactly the way you are describing it. AT&T rep also couldn't figure it out. I have ok data for about 30 seconds before it essentially goes out. If this were a land data connection, I'd say I was experiencing massive packetloss after it drops down from LTE.

AT&T has an app in the App Store called "Mark the Spot" wherein you can send diagnostic data right to AT&T about poor performance -- including geotagging if you give permission to the app to send that.

My iPhone 5 has done exceptionally well in LTE areas, though I cannot quote you numbers right now. I can tell you it's considerably better than my home DSL.

We are talking about data while on a call. My LTE speeds are exceptional, but are only reachable while not on a call, since we get dropped down to 4G non-LTE during a call.

I am having this very same issue. I have tried in different locations as well just to make sure it wasn't an issue with the cell site that I was on. When I'm not on a call I get speeds at an average of 5Mbs down and .5Mbs up but when on a call on 4G I'm getting Pings of around 700ms and .22Mbs down and .07 up. I don't think that this is a SIM Card issue like the AT&T Rep said...

It would be nice if other folks with different GSM LTE carriers (not AT&T) could chime in and report their speedtests while on a call.

Noticed that if you you disable LTE, is doesn't help the issue.

For more detail...

It drops down from LTE as we all know it should when a call is initiated(the indicator says "4G"). However, for the duration of the call, data transfer is near zero. I may get sporadic 1 second of data transfer, but otherwise anything I attempt to do while on the call will give me a server not responding. Once the call ends, data transfers are back to normal on 4G, and then it jumps back to LTE after 10 or 15 seconds and data is fine there too. I was in chat with AT&T for almost an hour yesterday and they pointed(obviously) at a possible iOS 6 bug.

Steps the AT&T tech had me try:

Restart iP5.

Reset network settings

Turn off iP5, remove SIM, wait for tech to do some setting reset on his end, and then insert SIM back in, turn iP5 on, and check.

Backup/Restore.

None of these steps appeared to alleviate the problem. I've tested this in 3 locations around the Los Angeles area, so it shouldn't be isolated to a specific tower.

Something worrisome that I have been able to test though... on my 2 parents iPhone 4S', one running iOS 6, one running iOS 5.1.1, the phones have the same problem. I don't think my old IPhone 4 had this problem on the lower HSPA network, vs HSPA+ that the 4S is accessing, however I am no longer in posession of that phone to confirm that with.

I didn't have this issue with my iPhone 4 on iOS 5.1.1 either... I updated my iPhone 4 to iOS6 when it was released but didn't use data while on a call before receiving my iPhone 5 and getting rid of the 4. I will try to have someone else that I know with the iPhone 4 and 4S(iOS 6) test this for me.

After discovering this same issue I spent about 3 hours on the phone with AT&T, who then referred me to Apple. Since I really wanted this fixed, I capitulated and when through the restore process to make Apple happy. They agreed and opened a repair ticket. HOWEVER, I started to do additional testing and asked friends to do the same test. (Ensure LTE is off, since it will not be used during the on call data session, use the speedtest.net app and get a base line, then start a phone call, while the call is going run the test and records the results) They recieved the same types of deltas between on call and off call data. Also note, they are on different hardware and OS's, so this is not an Apple problem. Your results will vary depending on area, but one common factor is the masive decrease while on a call. For example,

off call, 94ms ping, 6.29Mbps down, 0.68Mbps up

on call, 234ms ping, 0.54 Mbps down, 0.01 up

That upload speed while on a call is very consistent at 0.01 at all the test sites (about a 40 mile radius in Orange County and Inland Empire [Southern California]). There was one test that came back 0.00, it may not have been able to complete the upload in a timly manner.

I went back to AT&T spent another 2 hours, many transfers later, a ticket was opened for field techs to investigate. Two days later (today) I recived a call back stating that the issue was resloved and it related to visual voicemail, and to power cycle my phone and all would be well. It was not. No change in data speed was detected.

I called back and spend another hour on the phone and was able to get the ticket reopened.

I recommend that you call AT&T and push this issue. They need to know that more people are having this issue. If you do use "MarkThisSpot" you may want to ensure that you have a phone call going when you start the test, as it will do a 30 second diagnostic before it completes the submit. (I hope that data includes a bandwidth test)

First of all, I d like to thank you for very informative post and excellent and persuasive troubleshooting. Your information points me to possible understanding, that it may be just the normal situation. I d like to get a little more info, in order to establish base line, especially with different IOS's. Very intelligent and helpful conversation topic. Thank you guys, not very often that forum is that helpful. And I am sure many people will find that discussion useful.

Had a colleague try running SpeedTest while on a call on an iPhone 4 with iOS 6.0 and the data was also very slow.

I have this same issue too and I posted my results Here and Here .

I've tested it with different iPhone 5's. I personally have a 64GB Black AT&T iphone 5. Something is going on here and we need a solution.

I talked to AT&T yesterday and this has been identified as an iOS software issue as multiple folks across the country have reported this issue to Apple and AT&T. AT&T said Apple is working on an update to 6.0.1 to correct. This is good since I've spent hours on this including multiple restores, a replaced nano-sim and a new iPhone 5 from Apple.

I realize this thread is a little old but I am having the exact same problem. While on a call the phone will only get internet speeds of .50Mbps down and .01Mbps up and is basically unusable. I went through tech support with AT&T and they said get a new sim card. Did that with no improvement. They said go to Apple, did that and they gave me a new phone and sent me on my way. I tested in the apple store and it did the same thing. They said it was something with my backup so they restored as a new phone and it still does the same thing. They then said they had never heard of this before and it was a problem with the sim card or my AT&T account. I went back to AT&T and they said we don't know whats wrong and sent some report to their network support and sent me on my way.

While at AT&T they also said they never heard of this problem before but when I had them test it on a display phone it was doing the same exact thing. It's all very frustrating.

I saw a newer AT&T Talk and Surf commercial today (11/29/2012) during the morning 'Today Show'. The commercial "AT&T TV Commercial - It's Not Complicated 'Laser Boy' " can be viewed here http://www.youtube.com/watch?v=3WpoxqoX96E . So AT&T is still hyping the fact they can talk and surf even though the iPhones don't currently do it very well.

In my opinion it is not your phone. This is an AT&T issue. Tests I've run with other people show that is issues exists on other makes of phones.

I think this should be moved to class-action law suit status. AT&T is clearly deceiving the public with their claims.

I've spent at least a dozen hours on the phone with AT&T reps, the last one I spoke to on the issue was suprised to find that he got the same results at his call center in Washington. He said he would get back to me... never did.