how to call japan mobile frm UK?

I live in london and i want to call to my gf's mobile who live in japan , tokyo right now the number she gave to me is 080xxxx xxxx. I've tried all the area codes i know , pls answer my question , thank yuuu!

Japan has just one dialing code, and that is 81.

So the number would be:
0081-80-xxxx-xxxx

just click the sign +81 then remove the 0 from cellnumber ex. +81800000000.
hope this can help you!

I don't know about the UK, but each phone has a process to "dial out" or "international call" that you have to dial first.

Followed by the country code of Japan which is 81.

In my experience , unless the Japanese cell phone is set up to recieve international calls , you will not be able to get through

Hmm, that's interesting. I've used cell phones from every major carrier in Japan (au, softbank, docomo, softbank prepaids) and they were all set to receive international calls by default. I thought that was an industry standard, but I suppose anyone can change their phone settings to deny international calls.

Anyway as others have mentioned you need to dial the international access code first (00 for the UK), then Japan's country code (81), and then the cell number minus the first 0 (80-xxxx-xxxx). There are no area codes as Japanese cell phones do not use area codes. So dial:

00-81-80-xxxx-xxxx

more info here:

http://www.japan-guide.com/e/e2223_how.html

Have a smartphone dialing application in your mobile phone that will let you dial numbers directly from your contact list.

I suggest for Pingo EZ Dial that is available to different mobile phone models with rates the same with its prepaid calling card service.