if hes pakistani tell him: Ahista bhonk bh*& c&o%!!

if indian tell him: same as above

If egyptian: reciprocate with fake call with even louder voice everytime

If english: stare at him for abnomally extended time

If philipino: request him, he wont do that again

PS: Any of the abovecan be tried on all other nationalities, am sure one of these tactis will work.