When you phone him up, tell him your name and who you got the number from. Just introduce yourself pretty much. Say your good buddies with so and so and tell him you are looking for a hookup, or for some "dangerous goods" Just don't come flat out on the phone saying you want cannabis or drugs. Keep it on the down low.

If he is more than happy to help you out, ask him if you can stop by or meet him somewhere for a bag. LOOK CAREFULLY inside the bag before you make the final purchase, or, at least ask him to hold a bud or two in his hand so you can see what you're buying.

Or you could just takethat risk and just buy some. Start with a low amount first like an 1/8 or a 1/4.