There is no "free" local call with Skype unless you get an unlimited talk time subscription. Please try to understand how it works.
For instance 1.7 cent (EUR) per minute to call Japanese land line, plus connection charge. You pay this rate regardless of where you are calling from (Japan, US, or the space station)
Your registered number would be located in a country where your callers can call for the lowest possible charge.
Pocket WiFi is rarely truly unlimited. There is usually throttling mentioned in the fine print, if they decide to include it in there.