My 3G doesn't work on iPhone?

I can use Internet, Facebook, twitter etc at home using the WiFi but whenever I leave the house and try and, for example, search something on google, it come up with a message and a grey compass basically saying to reconnect the Internet.
What do I do to fix this?

Do you have a internet data? If yes, what service is it?
And make sure the cellular data is turned on in your iPhone's settings.

Mine does exactly the same, I just thought I had a crap network, since t mobile and orange merged to EE It's been rubbish, be good to know its not that and I can fix it.

You'd have to talk to your carrier about that since the 3G is their responsibility.

Help My Iphone was perfectly working. 4 days ago this problem occurs