No phone signal and data

[Kayem]

My son has an Experian E mobile phone. Lately, for some reason his phone can't receive any phone signals and data. It works with wifi though I swapped SIM cards with him. Both are from the same provider and are of the same size. His worked on my phone but mine didn't on his phone. We have reset his phone but it didn't help. Can we please have suggestions to get the phone working again.