Please help

Google this Using this Search Queue:

"your carrier may charge for sms messages used to activate icloud" site:discussions.apple.com

1. Solution 1 - Turn off Apple ID, iMessages, & Faceapp > Reboot > Press Cancel at Reboot
2. Solution 2 - Send an SMS Message form iPad to iPhone

And there's lots more... So try all and see what works.

Initial and continuing activation of iMessage and FaceTime on an iPhone requires an international SMS. If your carrier is not a supported carrier (doesn't have a specific agreement with Apple), you'll see charges for international text messages on your bill if you use FaceTime or iMessages. People with supported carriers never see the charges.