Phone calls

I would like to know how to make call via handphone and land phone in Japan (Tokyo/Osaka/Hakone). Is there a unique no. which I have to call before the telephone no.? I would presume that the cost for calls via handphone will be based on the user local network provider. What about land phone (e.g. calling from hotel room), how do they charge?

In particular, I may need to call the following places:
In Hakone : 0460-XX-XXXX
Tokyo :(81)(47)XXX XXXX
Osaka : 06-XXXX-XXXX

Will it be more cost effective to buy a prepaid card?

Thank you.

You should dial:
0460-XX-XXXX
047-XXX XXXX
06-XXXX-XXXX

In Hakone : 0460-XX-XXXX
Tokyo :(81)(47)XXX XXXX
Osaka : 06-XXXX-XXXX

Will it be more cost effective to buy

0460, 047, 06 are area codes.
0460 is for Hakone, 047 is not Tokyo but Chiba prefecture, and 06 for Osaka.

81 is the country code for Japan, no need to dial 81 when making a call within Japan.
Area code is necessary when making call from outside the particular area.

If you are calling to a number in Osaka from outside Osaka, you start diallling with 06.
If you're calling in Osaka, omit 061.
Same goes with other area codes.

When making a call with a mobile phone, always dial from the area code wherever you're.