I have the 3G Wifi 64Gb iPad 2 I have a sim card from my Canadian 3G carrier no contract connectivity payable monthly, only valid in Canada. If I goto US for a vacation can I goto a carrier and purchase a similar sim card for use in the US? If I roam on my canadian sim card I get charged an exorbitant roaming charge. Something like $2.00 per megabyte. any guidance appreciated. Roy Sletcher Ottawa, Canada.