Tobi's Spooky Expiriences: The fourth voice

So, one evening I was sitting with my friends talking on skype. We were doing our usual bad impressions and character chat until about ten o'clock or so. I shut down the computer I was on and moved to my phone where me and my two other friends could talk more freely. 

We were going on about one of my comics clear into the dead of the night. Everyone in my house was asleep and I was quietly trying to procrastinate my sleep because the conversation had gotten interesting.  For the life of me I can't remember what part of the comic we were talking about at the time but it was fun nonetheless. 

As it neared one the call had gotten progressivly quieter, this was mainly because I didn't to wake anyone.  My friend had been sharing his idea for a character when I heard a faint voice. It was a female, very broken up and choppy as if her call was dropping. She repeated "Hello? Can you hear me?" three or four times before I stopped him. 

When he asked why I had interrupted I asked him how many people were in the call. He told me aside from himself it was just one other male and myself. Following his answer there was a concerned 'why'. I told him I needed to double check because I heard someone asking if I could hear her. 

Both him and the other friend on claimed they didn't hear any voices besides mine. I ruled out that it was from them because both of their households were male dominated, aside from my friend's mother (who was asleep at the time) I was the only female. 

After I had asked about the voice I didn't hear it anymore and shortly after we ended the call. I haven't heard her voice since but it was a rather creepy experience.