PAYG SIM card.

[POR34]

I've bought many tickets for concerts in the USA from ticketmaster. I use ticketmaster UK for over here and have a separate account with ticketmaster.com for USA concerts.

[Incarniac]

Originally Posted by dazzabird

I’ll have it to try

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Originally Posted by Dr.JumbaJookiba

PM your address then, I'll post it later today

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As far as I am aware, H2O do not offer any roaming packages and you have to be within the US (and reach of the AT&T's network that they use) to make and receive alls and texts.

At least that's what their FAQ says when searching for "roam" or "outside":

• Can I make calls from outside the U.S? No, you can only make and receive calls from within the U.S. and its territories including Puerto Rico and the U.S. Virgin Islands.
• Can I send messages while outside the U.S? No, you can only send and receive text messages from within the U.S. and its territories including Puerto Rico and the U.S. Virgin Islands.

A cursory glance also implies that you need to be within reach of AT&T's network to fully initialise the SIM card in a device (though you can set up account and request activation online, I don't think that'll fully set everything up).

(I vaguely remembered some of this from looking up H2O a few years ago as I was looking at them for using with the US, but in the end decided against it and just went with the roaming package of my UK network. The above is from having a quick look again just now.)