I replied to a similar query earlier:
http://community.48months.ie/t5/Need-Help/Internet-not-working/m-p/39903#M16311
Follow my suggestions there and post back to let us know how you get on.
As it happens the other user is also on a Samsung Galaxy phone.
That may or may not be significant - it may just be a coincidence.
But it's worth noting that next to Apple iPhones, Samsung Galaxy phones seem to generate most of problem queries around here and elsewhere on the web for various reasons - and most often not due to 48/network specific issues.
That could also be related to the fact that they are both popular makes/models but they definitely do seem to have some odd quirks that do not happen with other phones (including the many cheapo Chinese makes/models that I have used!).
Hope this helps
