then it's a question on whether switching/testing T-mobile right now (stateside + international) versus getting a prepaid int'l SIM
the int'l roaming speeds is slow (128kbit/s, or 16kBytes/s), but calling USA numbers is only $0.20/minute
If you want high speed data and not much calling, I'd suggest a prepaid SIM like the 3UK that I listed
more options:
http://prepaid-data-sim-card.wikia.c...uropean_Union2
And, I'd not get a chance to test T mobile out in the states as well without committing
You can always pay $30 for 1 month of T-mobile prepaid in the states to test their network
http://howtoretireearly.net/the-tmob...-prepaid-plan/
You won't get the best experience testing a iPHone 4 on T-mobile. iPhone 4 is missing LTE, especially their low-band which gives you more coverage/building reception
(if tmobile has lowband LTE in your area. your iPhone 6 doesn't support this lowband either, need a 6S)
http://www.cnet.com/news/t-mobiles-l...you-go-inside/