It happened around 2007/08 when i was chatting with one of my friends trough mobile phone (in my room). Well we chatted for hours because she had free calls. As we were chatting she said she will put me on hold that she needs to do something. So i was still holding my phone next to my ear in case she remove me on hold. While i was still listening some scary noise came from my phone, it was really really creepy. I got scared of the noise and I threw my phone. When i picked up my phone to see if my friend is doing a prank on me or something, I was still on hold. 

When she came few minutes later I asked her if she did something, she had no idea what i was talking about....

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I just remembered that this happened to me as well, some things I forgot. But it comes to me from time to time when I try to remember this creepy happenings..