Check your APN settings. Go to Settings, More Networks, Mobile Networks, Access Point Names. Make sure there is nothing in there that looks like ATT.

So I have noticed something using T-mobile. I cannot leave messages on answering machines. When the answering machine picks up, I get a voice prompt telling me that the party is unavailable and to try again later, then it hags up. Interesting that this does not happen using my Sprint phone or any land line, just TMobile. Any way to turn this off?

T Mobile Global data coverage
 

The T-Mobile app for the iPhone mentions a different configuration.
APN: epc.tmobile.com

Thanks for the heads-up.

While I was in China & S. Korea, I didn't know what to check, and did nothing.

Now, I am back in USA, the APN setting is epc.tmobile.com (not ATT)

So is it necessary that I check and set the setting and leave APN to BLANK whenever I am overseas?

T Mobile Global data coverage
 

Hi,
I found it before but not anymore. Sorry

How do I set up my iPhone ( and T-Mobile account if needed) to ensure that I get the free included data etc but won't be connected to a not included network.
I.e India > Phone should connect
Bhutan > Phone should not connect (unless to the Indian carrier) as otherwise the costs are astronomical

Thanks

It's not a matter of the phone connecting or not connecting. When your phone first registers in a country, you get a text message from T-Mobile. It will tell you either: a) you're in a country with free text, data, and US$0.20 voice calls, or b) you're not and have to pay standard int'l roaming rates. If it's option b), then data is disabled unless you key in and Send the unlock code which is provided in the text message. Since inbound SMS's are free, unless you key in the unlock code for data, there are no charges, as you can avoid placing/receiving voice calls and sending SMS.

Great. That seems to be too customer friendly for a wireless carrier ;)

Thanks for the info

I've been reading this thread for awhile and have come to the conclusion that the different equipment being used might be to blame for the inconsistencies we're seeing in the reporting here.

For those reporting success/failure of service on their trips, could you also post which *specific* phones you're using?

For example, a Verizon Samsung S5 only has LTE bands 4 & 13 available on it. 13's only used in the USA, so this phone only has 1 LTE band it can operate on internationally. A T-Mobile S5 has LTE bands 1,2,3,4,5,7,8, 17. Similarly, I'm not sure if the Verizon S5 supports HSPA+.

There's also the possibility that the APN settings in use by some (in particular non-T-Mobile/ BYOD phones) may not be optimal.

Yes, the phone bands are very important. It is not just the general model itself, either. I ended up going with a LG G3, but choose the D850 model (the ATT version) because it had LTE band 3 which is important for the UK, while T-Mobile's own version, the D851, did not!

a lot of int'l roaming networks don't allow LTE. only 3G (or 2G)

might be better to check UMTS bands (below)...

https://en.wikipedia.org/wiki/UMTS_f....28UMTS-FDD.29

and cross-reference the foreign network

http://prepaid-data-sim-card.wikia.com/

Which phone model do you have?
 

http://www.gsmarena.com/ is good place to find which bands are supported for specific phone models & variants. Just search for the phone and expand under Network.

IE Samsung S6
http://www.gsmarena.com/samsung_galaxy_s6-6849.php
http://www.gsmarena.com/samsung_gala...cdma)-7164.php

There are multiple versions with specific model numbers under "Available versions" and the matching network bands for 3G/HSDPA in Frequency MHz. LTE is usually listed by Operator bands (Frequency MHz).

This map is also handy for referencing 3G Frequency by carrier & country.
http://www.worldtimezone.com/gsm.html
Most are consistent with what was available in 2013.

This one is kept more current and provides more technical details
http://www.spectrummonitoring.com/frequencies/

Is your GS4's firmware up-to-date as they should? For your next trip (if returning to same places again) - check your APN settings, devices running Androids on 4G LTE might want to try using fast.t-mobile.com, instead of the one with epc.xxxx while abroad. Also, try toggling network type between LTE and 3G - power cycle/reboot your GS4 and see if it will register automatically on the local partner's system.

While taxing along the runway @ICN, switched on my Nexus 5 and within moments, got the Free T-Mo Msg: Welcome to South Korea, etc. on the device. Nieces that were traveling with us initially had trouble with data on their iPhone 6+ (Simple Choice Plan, Family Share ones) so they placed a call back free to the US & spoke to T-Mo (+1 505-008-3793) and had that resolved/fixed promptly.

Just about everybody in Seoul is walking around with one of the Samsung's phabet so it's hard to imagine that yours were acting up - but, I did have a saved note on SKTel's network - "South Korea does not have GSM, they do have UMTS-2100. So, you need a phone that has UMTS/3G/HSPA+ 2100."

Perhaps that explained my unlocked iPhone5s (from VZW) registered more easily on SK's system without playing with the APN, etc. We were also in Taiwan for a week on a group's island tour & had no issues at all - but, didn't travel to China so ...

Ding, Ding, Ding @:-) This ^ - spot on, 3G/2G is all one need or will be using with global data roaming under T-Mo's plan - and I know last month, we had better than 2G data in most of Korea & Taiwan traveling under those plans.

Generally speaking, smartphones sold/targeted for the North America markets aren't always compatible with the rest of the world / global use while traveling - forcing some compromises. And, that is - up until very recently, usually involved popping out & in different sim cards, sometimes using the adapters - switching devices & remembering the APN settings, etc. T-Mo made it a lot easier & simplier, haven't touch that micro-Sim slot in almost 2 years since switching ... just power on & viola, service with the "Welcome to - - - - - - " MSG.

Even here in the US, there are still spots with less than optimal coverage - sometimes, mine will switch/show the "H" symbol instead of LTE, but - data is still fast, in fast - very fast, so I'm not worried; and, working out of the home office & a few other places with Fios coverage, that's just as nice if not better with turbo speed & low latency connection.

Perhaps that VZW unlocked Samsung is more than adequate to handle T-Mo's global data roaming - pop in the new Sim & just go enjoy the vacation/trip.

** On a related note, just saw that Nexus 6 (XT1103) 32GB model is on sale on the "Bay" for $300 shipped, 1 year warranty - factory unlocked ... not a bad deal at all.

less than optimal?

I live 50 miles west of Boston and I have a very hard time picking up T-mobile signal AT ALL in my home town. Fortunately (at least in this one case) I also have a work phone that is on Sprint, so I am covered. But T-Mobile does seem to have strong signal in the cities, which is where I need it most when I travel.

It definitely connects to LTE in Canada (when available), so it definitely helps if your device supports the correct LTE bands.