I get one generic spam phone call every month or two. My phone number has historically been on whois records for a couple of domain names, so I sometimes get related spam (your website is broken, you want to pay us to make another, right?), largely from only one or two entities despite being asked to stop it and being reminded that they’re breaking the law (I’m on the Do Not Call Register, have been as long as I’ve had the number, over 7 years), almost always from 07 or 08 phone numbers, but just
occasionally from 02 or 03 (just a couple of days ago I got two in one day from the same company, even the same
person I think, once 07 and once 03). I don’t know if I’ve ever received a legitimate call from outside 03 (Victoria, where I live) or 04 (mobile). Since I started using it for business as well, I’ve got a very small number of other calls as well (maybe three or four in a year).
My phone number can be trivially found, if someone wants to target me, in all its 2¹⁵‐suffix glory. My only defence is presence on the Do Not Call Register. If you’re not on it, try it. (I don’t really understand, from a serving-the-people perspective, why they don’t just abolish it and apply it to everyone—I can’t think of any reason why anyone would consciously choose not to be on it.)