IPhone 5 cellular data services failing

Question

ISSUE/SYMPTOMS:  iPhone 5 ONLY: Cellular Data stops intermittingly, cellular data locks up without warning, Wi-Fi data connection not working on occasion, iCloud contacts, calendar and reminders not updating, Find My Phone not working, mail or Internet not available or server time-outs. No error messages though. All of these are symptoms of no data service. Problems seem to be related to iPhone 5 failing to switch between LTE and 4G or 3G data services on AT&T.
My iPhone 5 32GB AT&T version (iOS 6.0.2) along with my clients and family using iPhone 5 in the state of Oklahoma are having this issue on their AT&T iPhone 5's:  no cellular data connection re-established if at anytime the LTE connection is lost or weak.  As with iPhone's prior to iPhone 5, the iPhone 5 is supposed to drop down to the next tier of data service and re-connect to cellular data service when the higher speed cellular data service is not available.  Apparently this is not working well on the iPhone 5.
What led me to research this LTE issue was that my iPhone was not syncing on iCloud with contacts, calendars and reminders with my other iOS devices.  Other times this issue became apparent was when iMessage quit sending and receiving until I would reboot my iPhone (sometimes it would finally send the message as a “text message”). When I had these problems I also found out I was not getting any cellular data service for Internet browsing, mail, Maps, Find My iPhone, etc.  This would happen without notice. In other words I would not receive any notice or error message that data service had stopped other than the fact I was not receiving any mail, iMessages, or iCloud sync updates. My only resolution was to reset or reboot my iPhone several times a day, and that would resolve it about 70% of the time. 
I have talked to Apple Support on 2-3 occasions in the last week and AT&T Support twice in the last 2 days.  If it is really true, only the AT&T Technical Support Advisor informed me of a nationwide issue relating to iPhone 5 and LTE:  iPhone 5's are not re-connecting to 4G or 3G cellular data service once the LTE data connection is lost or dropped... the voice calls continue to work, but cellular data service fails and stays locked up without an error message until the customer reboots the iPhone.
Obviously this is very unacceptable. We depend on these data services and at minimum need to know when it stops working instead of finding out from a phone call that someone sent us an important email or something.
The AT&T representative also said that both AT&T and Apple are aware of and are working on the issue as it is a nationwide problem with iPhone 5 and LTE. The Apple Support Advisors I talked to made no mention of this "known" issue. AT&T said that it is partly AT&T responsibility because the capacity of LTE is overloaded and cellular data connections are dropping because of the lack of coverage and/or capacity. They actually refunded my data service for a whole month in apology for the inconvenience (I did not even ask for that--I just want my data service to work).  But they also said that Apple has responsibility in this issue because the iPhone 5 should drop down and re-connect to the next lower tier of data service when LTE is not available or lost; instead, it is locking up somehow or it still thinks it is connected to LTE when it is actually not. I don't know how accurate these statements are, but my problem is real.
TEMPORARY WORK-AROUND / FIX FROM AT&T:  Disable LTE on the iPhone 5.  Or when you figure out that data is not coming to your iPhone, use Airplane Mode ON/OFF for a few seconds to force re-connection to a tower without rebooting the iPhone.  You can Disable LTE on the iPhone 5 in SETTINGS/GENERAL/CELLULAR. I have disabled LTE on my iPhone 5 and have not had any of these cellular data issues since. 
Disabling LTE is not acceptable either, but it is working. At least I seem not be losing connection or locking up without knowing it.  In my office over the course of a day, my iPhone 5 will jump back and forth on LTE and 4G sitting in the same place.  Disabling LTE has stopped this and the problem, but the iPhone 5 should switch cellular data services seemlessly just like the phone switches towers on a phone voice call seemlessly (most of the time).
WI-FI ALSO STOPS WORKING SOMETIMES AFTER THIS LTE disconnect / lock-up issue:  That has been my experience along with my clients and family as well. If you use Wi-Fi a lot on your iPhone it will hide this LTE issue until you leave your Wi-Fi and get on LTE and then drop LTE (silently) and then go back to your Wi-Fi.  My experience has been I have to reboot the iPhone to even get Wi-Fi working again after that happens.
I do not know if some of these comments and analysis are really accurate or valid or not... all I know for sure is since I upgraded my iPhone to the 5 along with my other family members and clients, we have had "no data" on many occasions and are continually rebooting our iPhones and looking for what is wrong. 
My questions to the support community are these:
     1. Is anyone else having this issue? Or is it just me and my few? Maybe a lot of people do not realize they are not getting their data because they are on Wi-Fi most of the time or they are just rebooting and not trying to identify the real problem. AT&T said it was nationwide iPhone 5/LTE issue.  Anyone else heard that from either Apple or AT&T?
     2. Is this an iPhone 5 / Apple issue or is AT&T solely responsible? Or is it both? Where do we get a solution??? Is AT&T LTE holding false connections with iPhone 5 or is the iPhone 5 failing to recognize a dropped LTE cellular data connection and then failing to attempt to re-connect with 4G or 3G?
     3. Did I miss where this issue is posted? I searched Apple Support and Communities and did not get any hits.  Any updates or further insight on the issue? Any other fixes other than Disabling LTE?
      4. If this is in fact a real issue belonging in part to the iPhone 5, we need to escalate Apple’s attention to it.
Thanks in advance for your help and feedback.

Answer 1

Thank you fellow users and experts for your feedback and updates. Sorry about the large font on the original post... accidental via cut and paste.
I have escalated the issue with both Apple and AT&T.  I actually got senior level troubleshooters from both Apple and AT&T on the phone at the same time... rare moment. Here are the key points of the update:
     1. AT&T did NOT confirm the earlier statement by another AT&T Technical Support Agent that this was an emerging nationwide issue about iPhone 5 and LTE losing data connection and not reconnecting at a lower level or re-connecting to LTE once the signal came back. So that earlier statement was not accurate as suspected by all of us. The senior tech at AT&T said he has seen this issue sporadically over the last month or so, but only with about 3-4 customers.  He said it seems to be location or phone dependent (some phones not all phones).
     2. The Apple Tech was satisfied that all that could be done to eliminate my issues possibly relating to my instance of software / iOS had been accomplished except erasing my iPhone and restoring as a new phone (I have avoided this inconvenience with the argument that other family/clients with the iPhone 5 have had the same problem).
     3. AT&T went so far as to examine which towers I had been connecting to over the last week and looked at other technical data that could possibly explain the issue. I now know I have 3 towers that provide LTE within 4 miles of my home/office, one within a half mile.  But so far there is nothing to explain or even properly identify the issue.  AT&T offered me to take my phone to an AT&T store, try to force replicate the problem there, if so, the store would put my SIM card in a brand new iPhone 5 (just to test) and try tor replicate the problem again. If replicated on a new phone, there is a deeper issue; if resolved on a new phone, the answer is obvious. I have not taken the time to do this yet.
     4. On Friday, Jan 4, 2013 while talking and between the tech support calls (on a different phone), I was able to re-create the problem 2 separate times in my home/office by forcing my iPhone to weaken its connection to service (burying it under electronic gear) and then waiting a few minutes, then trying to browse the Internet--no data service unless I manually reset the connection.  I am only able to cause the issue to occur if there is at least 15 min of idle time after a weak signal condition AND only if I don’t completely lose a connection to cellular voice service. It seems that if you go down to NO SERVICE the phone will do new a search and keep searching until reconnects to LTE or other signals correctly, but a weak connection seems to be strong enough for voice service but can sometimes cause the LTE data service to stop without reconnecting to LTE, 4G or 3G unless I manually intervene. It also seems that idle time with a weak connection is also necessary to re-create the problem manually.  Since Friday, I have not been able to re-create the problem. This has been an intermittent problem, so who knows.
FYI, I have never had this problem with my new iPad (also on AT&T LTE) that has been with me when the iPhone fails to have data service, but my iPad is never in my pocket or other places with perhaps less signal.
Again, if you are connected to Wi-Fi on your iPhone 5 most of the time, you may never notice this issue if you are even having it.
So far no progress on the real issue or resolution, but both Apple and AT&T have put forth very admirable effort.
If you or others you know are having this issue, please take the time to post a reply to this issue. Thank you.