Data

[Alpaca123]

Hello I am in America, before I left home I called 150 and they told me I could use my phone in America for £25 per month

[bristolian]

Does your phone show a connection to a US network?

[bdg0514]

Hi,

have you checked your Data Roaming is on and automatic network selection is enabled? 
also is your phone connected to any usa network for example AT&T or T-Mobile when i was there in the summer my EE sim preferred AT&T over T-Mobile most of the time

[XRaySpeX]

As you are on contract, did you activate roaming on your EE a/c before you left UK by texting ROAMING to 150? Having a roaming billing add-on doesn't of itself activate roaming on your a/c. Having roaming activated on your EE a/c, not just on your device, is crucial to using your contract SIM abroad.

Often just rebooting the phone is the simple remedy. Also try selecting a network manually rather than auto. Otherwise you need to call CS to get your roaming activated. Try calling CS on the Freephone no. in my sig. on Skype over WiFi. It should be free.