Early one Saturday morning while my DH was out with the dog, our landline rang briefly and then stopped. I checked the number, and it was DH's parents, so I suggested my DH rang them when he got home.
He did, and got through to his Dad, who wasn't the usual phone answerer - he didn't like talking on the phone much and his mum usually took calls, but she'd popped out, so DH and his Dad had a chat for the first time in a few months (we live at opposite ends of the country). DH's Dad was adamant no one had used the phone that morning, and so was DH's mum when she got back, so we couldn't explain the missed call.
That evening, we'd gone out for a meal - and sadly got a call that my DH's dad had had a sudden cardiac arrest, and died after being taken to hospital.
My DH said afterwards that if it hadn't been for the strange missed call, he wouldn't have been able to remember the last specific time he spoke to his dad - but thanks to that, he'd talked to him on what turned out to be the last day of his life.