Phone call causes LOUD screeching noise from unknown location near my apartment building

[KGG7]

Something really strange happened and I don't really know who to ask about it. I came here hoping to find some folks who are knowledgeable with electronics and signals who could possibly explain this to me, since it piqued my curiosity. Here it is:

I made a phone call from my room in my apartment. About 30 seconds into the call, my whole apartment became flooded with a very loud, piercing, high pitched noise. My first thought was fire alarm, but then I realized it sounded less like an alarm and more like some kind of malfunction from an electronic device somewhere.

At the time, I did not think it had anything to do with my phone. More on this later. But the noise was not emanating from my device (iPhone 7) whatsoever. I walked around trying to identify where the noise was coming from but couldn't find anything. I walked outside and the sound was audible from 20-30 feet away from my door, so the amount of sound being generated was huge. Enough for my neighbor to hear. She was outside and we went around the building looking for where the noise could be coming from. Our building is not directly under, but close, to some power lines. All of the utility meters are on the back of the building on the other side of the wall from my bedroom, where the noise SEEMED to be centered from. But it wasn't easy to tell exactly where the center was.

Meanwhile, the whole time, I had kept my call going and was keeping the person updated as this event unfolded. I decided to shut off all my breakers in my unit in case the noise was coming from a device being powered by my unit. After shutting all breakers off, the noise continued. This is a noise I have never heard before, and I've been living here for 5 years. Nothing like this has ever happened.

This is where it gets weird. I decided I would call my property management's emergency line, so I go to hang up the phone call and look up their number. EXACTLY down to the split second, when I press the button to end the call, the noise instantly stops. I can't believe it!

So it's either the most absurd coincidence ever, or my phone signal was somehow interacting with some electronic system in the area to cause this crazy noise. What in the world could have been going on here guys?

 

[Alec_t]

All of the utility meters are on the back of the building on the other side of the wall from my bedroom, where the noise SEEMED to be centered from.

Just a guess, but perhaps there's some anti-tamper alarm associated with the meters and your phone (or something else coincidentally) triggered it.

 

[duke37]

It would be a help if you said which country you are in and the name of the electricity supply company. It appears that the noise level is well above what a mobile phone can deliver.

 

[BobK]

I’ll vote for coincidence unless it occurs again the same way.

Bob

 

[KGG7]

Thanks for the replies so far! I forgot to add in the original post, I tried to re-create the situation several times with the phone call from the same location and it didn't happen again. I'm in california using sdg&e. Again, the sound was centered somewhere around my building but not directly from my phone. Tamper alarm is a good guess, but I feel like the pitch was too high and "screechy" to be an alarm. I could be wrong tho. I would have definitely thought it was a coincidence too, had it not ceased immediately upon ending my call. Maybe we'll never know! Just wanted to see if anyone's heard of something like this before. In my mind it would've had to be my phone's signal somehow accidentally triggering a resonance via one of the systems nearby. I don't even know if I'm using the correct terms to describe that, since I literally know nothing about signals or communication, but that's my best guess.