Try this:

Hey is that <name>,
alrite man, got a number off a mate of mine, said i can ring you for a weed/bud

now he will say what do you want,
tell him what you want (10 bag, 20 bag, 1/8th, quarter, half ounce) of (sput/skunk)

after you have rang him a few times, maybe ask him what weed he got? he might have two types dont forget..

if all goes well, say where and when, he might say you got transport, he might just say meet me at x at x.

If all doesn't go to well he will tell you to get bent or he might have no bud.