Airtel — When ever I try to call someone it says the number you are trying to call in not valid

This problem has been happening since quite sometime now. But the intensity of the problem arose when I tried reaching out to every single person in the family and in every single phone call it said that “the number you are trying to reach is nit valid”. The problem happens every single time until and unless there is an incoming call from any number. Then the outgoing resumes. So kindly look into this matter