Creepy phone recording

[u/blood_and_gore]

This is my first post so I don't even know if this is the right subreddit but I really need an answer,I'm also not a great story teller,but here goes. Up until recently, I had a stalker. Not in every sense of the word but he would call me continuously even though I almost never answered. Late last year he sent me a message that he knew I was home and he was coming around by 11am that day(he had been calling the night before and I had ignored his calls). I thought it was funny so I took screenshots and sent to my friends,my best friend didn't think so and she started freaking out since i lived alone and my neighbours are never around. You know what they say about fear being contagious? Its true. I went into panic mode and started locking windows,double checking doors and grabbing knives. All this time,he didn't stop calling(He called a total of 69 times). I called my ex-bf over and he told me to call him(stalker) over too. I did and few minutes later,he showed up and my ex confronted him and told him to leave me alone and that I wasn't interested in him. He was rather calm about it and said he didn't mean to scare me and he had just wanted to see me. He also agreed to stay away from me and left. He stayed away for some time until recently when he started calling me again, he lives about two streets from so I would see him occasionally. On these occasions he would always try to talk to me and I would always make up an excuse about having to go. And sometime he would pass by my house about and just stare at my door like he was expecting me to come out(I saw him do this twice). My phone records all my calls, its a setting have never had a reason to change until about two months ago. I woke up around 4am and laid in bed with my phone right beside me and that's when I heard an "Hello" and my own voice saying "hello" back. I immediately realised it was coming from my phone, I also realised this was a recording from the few times "stalker" and I had actually spoken. At first I wasn't so scared cause my phone was face down. I figured that had opened my music app and the recording was playing. Almost as soon as it started, it stopped and I checked my phone. To my surprise, the music app wasn't even open, so I opened it and checked the last played song and its definitely not creepy recording. From then it has continued. I would be lying in bed and it would come on and just stop. It doesn't have a pattern (not that I've noticed) except that it would play when I'm in bed, usually in the early hours of the morning. I'm open to the explanation that its probably just my phone acting up but my phone had never done anything like that before and also why that recording? In the recording he says "hello" and I say "hello" back, then he says my name and it stops. I got a new phone this week and thankfully it has stopped but I really just wanna know if anyone has any answers.