Hi,
I've recently switched from BT to IDMobile. One thing I have noticed is that the signal is definitely weaker in my region, RG9 postcode. Often it drops from 4g to H+ or just H which really interferes with internet usage. I live 9 miles from Reading, Berkshire, so I guess it's a lack of mobile towers of something. But it's pretty annoying and not something I expected give IDMobile is using 3 mobile.