My guess is your mom got fed up at one point and gave them a piece of her mind, so someone doing prank calls thinks she’s a fun target. If it’s idiots, not spam, then *57 and reporting it may work. I wouldn’t hold my breath though with our phone companies. Might work better if you mother “thinks” it was an obscene or physically threatening call.
Very few people call me on my land line, and apparently the only anonymous valid one is a health clinic. But, I also get weird calls on my cell. Once in a while it’s a robocall warning in Mandarin (the ultimate in Canadian spam) with what I assume is the standard warning to call back because the Immigration or Chinese police or someone is after me because of paperwork. (apparently the typical scam imed at Chinese immigrants). Considering the only association I have with China is applying for a visitor visa over a decade ago, I have to assume this is just scattershot spam. On the house phone, I have never gotten a voice message from spam. It’s been a long time since I got a call saying the RCMP were coming for me unless I paid… My wife at work says they got the “please pay us this unpaid bill or your power gets shut off this afternoon…”
When I get a weird call, 50-50 whether i decide to answer or just let it ring out. Usually it’s my cell, and it comes in waves maybe 2 a day to one every 2 days, and stops for a few weeks. If I pick up and stay quiet, a real human will go “Hello?” The autodialer simply assumes nobody there and hangs up after 5 or 10 seconds of dead air.
I’d love to be able to answer annoying calls with a fax machine noise.
They even spoof valid local numbers (but not the name). In the early days I got 2 or 3 calls saying “why did you call me?” I guess somehow the phone company blocks that now or they no longer find that productive.
My parents years ago had a feature (in New Jersey) where unrecognized or blocked numbers (like my unlisted number) the machine would answer and ask you to provide you name. It would then ring the phone and they would hear what I said for my name and the option to accept or hang up. You could program familiar numbers to bypass this.
I would be more worried about financial scams - everything from AI saying “Hi mom! I’m in a Mexican jail and need $1,000 for bail immediately” all the way to shady roofing and plumbing companies.