Hi Inku, Stanacard is the best calling card I have ever used. You can use the link here.

http://www.stanacard.com/?ref=254194

If you use above link to register, you will get $10 free with $10 purchase so with the total of 169 mins of high quality voice call which does not require pin to call Nepal.

Enjoy hours of talking with your friends and family in this dashain.

Happy Dashain