As others point out, it is cheapest to top-up friends/family in JA and have them call you after they turn them into international minutes. That costs them $1J/min to call you. I think they need a minimum balance on their phone of $1000J to convert them to international minutes by dialing some ext - no need to visit a store. Those $1000min are good for up to 30days - expire after that.
For times I need to call to JA - I have an account with http://www.nobelcom.com/.
No need to get a physical card, can setup pin-less dialing, automatic re-charging, etc. Variety of plans for different rounding times, connection fees, etc. I think they all do that now.
For me, a $40 re-charge usually lasts me 2-3 weeks - but many times I call and talk for the 2 min they are going to charge me regardless - and have my fiancee call me back with her cheaper minutes.
For all these cards, watch out for teaser prices. They all, including one I use, seem to have low prices listed prominently, but those are to land-lines in JA - very few PEOPLE have landlines, but is good for calling hotels and other businesses. Calling a cell phone in JA has a higher per min charge.
