I currently am using an LG phone with TMobile domestically in the U.S. I plan to give my current phone to sister, thus I am planning to buy an Iphone 5s on Ebay. I noticed they had a few options like GSM unlocked, TMobile, At&t, Verizon, etc to choose from in addition to color and memory(16g or 32g).

So my question is, should i get a GSM unlock since that should take care of not having to contact Tmobile about unlocking the iphone when i travel to Europe and also being able to use at home since it should work abroad and home. Or should just get the tmobile version and just let tmobile unlock it when i go to Europe and buy a local sim card there for use ? Or if i choose to use tmobile's plan, i don't need to call them at all since they have coverage in most parts of europe anyway.

I basically want the version that i can use in Europe and domestically(U.S) without hassle. Thanks.

Safest model is Verizon as their iPhone from 4s model up are all factory gsm unlocked - can use both domestically and abroad (except sprint carrier).

ATT and/or TMO might require carrier unlock for international and domestic.

For LTE service, 5 or higher should work. You should be able to get quality 5s on craigslist....meet the buyer at a network store to make sure it's a clean phone.

I thought Verizon uses CDMA

Verizon uses both CDMA and LTE and would support quad band HSPA. My recollection was a Sprint unlocked phone was the most versatile. I am going to go on a limb, however, and say that you want at least a 6. WiFi calling really isn't supported before that. In theory the iPhone 5s supports it, but there is a reason why most carriers have avoided it on that phone.

thanks. tmobile did tell me about free wifi calling when i travel abroad.

Depends on the model you get. The 6s model for Sprint/T-mo/Verizon is the same. AT&T model adds band 30 support, which I think is only used in the US.

http://www.apple.com/iphone/LTE/

I think all the carriers offer that nowadays. Verizon, AT&T, Tmo do...not sure about Sprint.

The phone model/specification and the phone carrier you use when overseas are some what different questions.
For overseas your phone needs to have the band used in that country.

Yes.

There are 30-odd (or more) frequency bands defined for use worldwide for LTE. It's not a question of just one or two bands per country.

Was just overseas and and text and data free was phone calls was 20c/min. I have sprint

Mod note - moved the discussion of wifi calling to a new thread.

http://www.flyertalk.com/forum/trave...i-calling.html

If the OP gets a Verizon iPhone for world travel, how well will it work on T-Mobile here in the US (LTE)

My older Verizon 5s runs TMO fine;newer Vz 6S+ was given to Mrs. first day I got upgrade and she's been on TMO since 9/25/15 without a problem anywhere (including Asia). LTE stateside works just fine on both models.

What about band 12LTE?

Vz 6s+ includes band 12:
http://www.apple.com/iphone/LTE/

I have an unlocked GSM (AT&T) Iphone 6, what would be the best out of the USA sim card option to use?
Wait till I get to wherever or get a Cricket or something?