How to switch from Prepaid to Postpaid

mobile-users-will-able-to-switch-between-postpaid-and-prepaid-using-otp
बिना SIM बदले ‘Prepaid’ और ‘Postpaid’ कनेक्शन के बीच स्विच कर सकेंगें मोबाइल यूज़र्स