Please follow the below steps
1. please check your mobile's network connectivity and after that please try to register with another mobile number
2. If still you are facing an issue - you can check your DND (Do not Disturb) services and deactivate it either by changing your phone’s internal settings or by contacting your respective mobile network customer care/** service provider (such as Jio, Airtel, Vodafone Idea (VI) BSNL etc.). and follow the DND Deactivation process.