This is probably the freakiest thing (involving phones) that's happened to me, coincidence or not:
One night, around midnight, me and my friend were walking through a creepy back ally part of town and passed a payphone that I happened to have the number to. I called it all secret-like without letting him catch on.
When it rung, I pretended to act all paranoid and scared like somebody was watching us. He already knew that whenever I see somebody walk by a payphone, I will call it and mess with them. I used this to my advantage by acting like somebody was doing the same thing to us (also, we had previously been talking about scary stuff like finding a bloody suitcase full of money, seeing a dead body, etc. so that helped set the mood.)
Eventually, I talked him into answering it and... I whipped out my cellphone and said, "What's up, buddy?"
He acted like he was mad at me, but I could tell he was at least a little bit relieved.
We both walked some more, and he told me how much of a jerk I was. But that's not the weird part. On our way back, about ten minutes later, we both walked past the same payphone again. And as we walked by it, it rung. I didn't call it, and my friend didn't own a cellphone at the time. It was after midnight at this point. It's silly, I know, but I got shivers because of it.
We didn't answer.