yes, he supplies you with his country, then phone number, then pin number in that order.
The usual process is:
1) Have a TRUSTED mm ready
2) the 3 of you meet in specific world/place
3) you give the MM the cash
4) the seller gives you the country, #, then pin
5) you login to your account and extend/start a subscription
6) a ) if it works move on to step 7
b ) if it doesn't work (invalid pin or phone number) inform the MM right away and he will return your cash otherwise,
7) Inform MM that pin works, and he will give the guy his cash and it's a happy story both ways

add the transaction to your signature for future confidence for yourself and others
Good luck.