UPI (Unified Payments Interface) is a method which allows you to transfer the funds easily. It is developed by the National Payments Corporation of India with Reserve Bank of India's (RBI) vision of cash-less economy. Recently Indian Gocverment announced an official application named BHIM (Bharat Interface for Money). As of now this payment applications will be available only for the Android platform.
Paytm now allows users to add money to their wallets via UPI.
Choose the payment method as UPI and enter your Virtual Payment Address and proceed. You will receive a notification on your UPI application requesting for the approval of payment approval.
You can add a maximum of INR 20000 to Paytm account at a time. As of now the payment using UPI is not activated on the Paytm application for android. It is enabled for iOS and Web only.