Boostbox - the users' mobile won't connect to the Bostbox.
They will need a 3G or 4G mobile to use the Boostbox. Check that 3G or 4G is selected in the mobiles' settings. Then check if the mobile number has been registered with the Boosbox.
If the SIM has recently been replaced, you'll need to re-register the mobile with the Boostbox. Please call PCS on 0800 11 44 33 to do this.