The UPI 123Pay service introduced by the Reserve Bank of India (RBI) allows users with feature phones to do UPI transactions. This can be done by dialling the number 080 4516 3666 from your feature phone. Your mobile number must be linked to your bank account to avail this service. Users can make UPI payments using sound-based technology and built-in apps.The UPI 123Pay service introduced by the Reserve Bank of India (RBI) allows users with feature phones to do UPI transactions. This can be done by dialling the number 080 4516 3666 from your feature phone. Your mobile number must be linked to your bank account to avail this service. Users can make UPI payments using sound-based technology and built-in apps.