I've spent couple of months in southern California and I was using my Jolla with a sin card, that I bought there (T-Mobile). It worked without any issues, also I didn't have any problems with roaming using my European sim card.

Thanks for the info. I might have a chance to pick one up and wondered how well it would work in the US.

Were you able to use 3G data though? Or at least multimedia messages?

There were no problems with 3G data, didn't had a chance to check out LTE. I've successfully received a copule of MMS-es with pictures, I haven't tried sending any.

Wow! But I thought t-mobile was 1700MHz / 2100MHz! I don't want to believe that you're lying to me, but... You've gotten my hopes up that I can use this on WIND in Canada.

Did you try any other providers or only T-Mobile?