[8.9" Kindle Fire HD Q&A, Help & Troubleshooting] Zanthexter:
I thought it might be helpful to share my experience getting my (now rooted, stock, with Google stuff added) Kindle Fire HD 8.9" 4G working on the T-Mobile network.

Getting the SIM card to eject using a paperclip was a royal pain in the ass.

You need a paperclip that's thin enough to fit LOOSELY in the hole. If you try to squeeze one in that's fat, it will jam the SIM edges to the case. Once you find one that'll work, it'll bend...and bend some more. I finally managed to get enough of an edge to stick out that I pried it the rest of the way with a screwdriver, with some minor scarring in the process. It's not really noticeable, but *I* know it's there. (To be clear, you poke the paperclip into the hole, push, and it'll eject. Theoretically anyway :) )

Once it's out though, things get easy. Just pop in the SIM, insert, change APN info as appropriate, done. APN settings can be found easily with Google. Removing it later was easy as pie. Paperclip, poke, eject. I have no idea why, maybe it's initially glued in or something. Nothing came out stuck to the SIM tray though and it's since popped in and out with no problems.

Now, here's the REAL kicker... I had planned to put the SIM from my T-Mobile hotspot in it. It just didn't occur to me to check to see if the Kindle used the same size, it doesn't. It uses a Micro SIM. Well, I didn't want to cut my hotspot SIM (I'm not yet sure if I'm keeping the Kindle or not), but I do have a Nexus 4...with a Micro SIM. So I figured, what the heck...

Damn if the thing didn't work. As far as I understood things, you aren't supposed to be able to use a phone SIM with a tablet in T-Mobile land. Maybe it's because I'm using a T-Mobile reseller, Solavei, but it worked fine with the Solavei phone SIM and APN settings. No issues at all. (Solavei is great, exact same service as I got from T-Mobile as a contract customer, but no-contract, cheaper, with more data.)

I happened to have to drive to Webster today, so I kept running SpeedTest.net every so often as I was driving across Houston mostly down I45. Here are the results:

Down	Up	Ping

1704	2157	110
1053	2102	102
1391	988	111
2872	943	914
4641	2145	100
5794	2370	115
11191	2267	139
2228	1335	113
1219	1401	90
144	96	802
18755	995	25

The 11k and 18k are not typos. I don't think they are glitches in the SpeedTest.net app either.

To give it some context, I was driving through rush hour which might explain a couple of the download speeds being lower than the upload speeds (busy towers) I also WAS moving, anywhere from 10-70 depending on how bad the traffic was.

Houston is in the process of being "refarmed" for the iPhone. So I think the 2 particularly high numbers may have been towers that were completed. Although, I suppose that it's possible that I roamed onto AT&T. (I can roam with Solavei) because the 18k number with the really low ping time looks like what I'd expect from LTE. T-Mobile IS doing LTE in Houston, but I haven't checked to see if the Kindles bands are compatible.

Anyway, while the numbers are not spectacular, if you have some reason to want to use the Kindle HD on T-Mobile's network, the speeds are certainly usable for email, web browsing, GPS, etc. My hotspot is paid for by work, so "Free" is a good enough reason for me :), and saving the hassle of having yet another device to make sure is charged, doesn't get lost, etc. while roaming all over the city is MAYBE worth the reduced speed. (I usually get numbers in the mid to upper teens with my hot spot.) The less stuff I have to plug and unplug from cigarette lighters each time I stop at a client the better.

Oh, a note on GPS. I initially had problems with it. It took a while to lock, and then wasn't accurate. After I let it update from 8.14 to 8.3 things worked fine. (I had rooted, installed Google stuff, etc, but not blocked updating figuring to just re-root at 8.3.) Google Maps / Navigation worked fine my whole drive. I'll try Co-Pilot tomorrow. (MUCH better live traffic data, or at least use of that data, than Google. Worth the $10 a year just for reasonably accurate ETA's.)

A couple further thoughts....

1) If the ability to use a phone SIM was NOT specific to my situation, that could give the Kindle some great options for mobile data service. T-Mobile has a $30 a month prepaid plan with 5GB of data, unlimited low speed data, and at the other extreme, a $70 plan with unlimited high speed data. Neither are offered for tablets.

2) It took a phone SIM. Gotta wonder... with the right ROM could you make calls? A data SIM blocks calls at the carrier level, but a phone SIM, well, as long as the hardware is there and the software supports it....

And before anyone goes off on the idea, OBVIOUSLY holding a 10" tablet up to your face doesn't work. But I don't hold my 4.8" phone up to my face either, it's called Bluetooth. The "tablet as phone" works as a second line. For example, as a work line. I have a couple of clients that do the "on call" thing, with a cellphone that get's passed from person to person at the start of each shift. That could actually work better with a phone-tablet, since they'd then have email, remote security camera access, etc. along with the ability to make calls. (Again, Bluetooth or just speakerphone works fine.) If you're going with the phone SIM for some other reason (cheap or unlimited data), why NOT take advantage of the ability to make calls?