I have had this happen a couple of times before. It probably happens at least once every two months, but this morning alone I’ve already had three calls from a “restricted” number, and when I pick up all it does it beep intermittently every other second or so.
I’m pretty sure it has happened on my wife’s phone before too, but not as often.
I signed up for one of those free trial fax-to-email services, and told ONE person about the number, late at night, so I could receive a fax immediately. That person sent the fax and went to bed. So did I. The next morning, I had a spamfax of some dodgy ‘investment opportunity’ in my inbox.
At one time around ten years ago I got so many spamfax messages recorded on my cellphone that I had to change the number. And since such spamfaxes usually tell you to read the fax to get unsubscription information, and there was no way O could get the recorded fax message out of my voicemail to a fax machine, I was stuck. Changing my numbewr was erasier than trying to forward it to a fax machine and hoping it would work, and then discovering that it didn’t.
Your spamfax call probably had no caller-ID info, thus came up ‘restricted’ or ‘anonymous’ or ‘private’ or some such on your phone’s display.