I can't turn on my tablet - Samsung Galaxy Tab S 10.5
Cause 5 of 10: Your tablet is locked to Vodafone
If your tablet is locked to Vodafone and you try to use a SIM from another operator, the display will tell that your SIM is invalid.
Solution: To use a SIM from another operator, contact customer services to have your tablet unlocked. Before unlocking a tablet, certain requirements, which may induce costs, need to be met.