I know you hear me!

Pet peeves. We all have them, and this has got to be in my top 3 .
Don't you just hate it when you go to call one of your friends, and as you're hearing the ringing on their end, you hear the beep that lets you know they're on the other line? Normally they'll pick up after 3 rings or so and let you know they're in the middle of a call and offer to call you back. Most phones now pop up caller id on these calls, so they'll know it's you...but still not answer.
It makes me sooooo mad sometimes. I'm just sitting there, hearing the beeping, and slowly feeling the anger rise. "You know it's me, it says so on your phone!" Then after no answer I get all pissed and usually ignore them when they call back. That's just the 5 year old in me I guess.
Most things I let roll off my back, but this one I just can't.