GRLmobile gives u:
We’ve met the highest standards in mapping our coverage for you, but 100% accuracy can’t be guaranteed. Coverage information is based on outdoor analysis and can be different when you’re indoors. There are a few things that we can’t control that can cause coverage to vary within a GRLmobile “coverage” area. For example, the age and type of handset, local weather conditions or areas of variable reception (e.g. basements, lifts, underground car parks, large concrete buildings, or road cuttings) may cause loss or interruption of reception signal.
*With National Roaming activated.