. .  and I got a puzzled Shaw landline call from a stranger who said "this number came up on my phone so I called it".

Clearly, some scammer has spoofed my number as their caller ID. If the number of such puzzled or angry incoming calls to me begins to become a problem, there isn't much to remedy the situation except to route such calls to voicemail, and there explain the situation and ask the caller to block my caller ID.  Eventually, the scammer will stop using the number as its value falls.

Is there a Shaw service that allows me to "whitelist" numbers and direct all others to voicemail?  I have reviewed Shaw's web stuff and only a blacklist exists -- and only 31 numbers long.