09-05-2012 20:06 - edited 09-05-2012 20:09
Providing he is using his UK phone
It will not cost you any more to text him and receiving text will be free. However, if he text you he will be charged
If you call him it will be the same for you but he will have to pay to receive your call and to call you.
Charges will depend on your tariffs http://www.o2.co.uk/support/internationalandtravel