My mobile phone is only showing a G icon as my network signal instead of something like H+ why?

[AC Question]

Mobile phone is only showing G icon.

I have just changed from a T-Mobile contract to O2 pay as you go.
Since I have done this my Note 2 is only displaying a G icon with no or very little internet anywhere.
Is there anything I can do to get H+ back or is something wrong?

 

[B. Diddy]

Re: Mobile phone is only showing G icon.

Welcome to Android Central! Do you know if O2 uses the same network bands as T-Mobile? If not, then you need to make sure your phone is compatible with the bands that O2 uses. To find out, you can do a Google search for "[your exact model number] specs" and "O2 network band."