Do you do social media from your phone? Twitter. Facebook. Etc.
Everyone I know that has given their number to Facebook gets more spam than Guam. Facebook is not free. They sell everything they can find out about you. Including phone numbers.
Do you do social media from your phone? Twitter. Facebook. Etc.
Right... not legal to call but who did that ever stop?
Just because YOU haven't added your phone number to facebook, doesn't mean THEY haven't associated your phone number to your facebook account. Everything you do on your phone is associated with your IMEI or ICCID, which is easily linked to your cell number. There are even services that "fingerprint" the browser you are using, which makes it pretty easy to identify different folks hitting websites even if you're going through a VPN service. The VPN masks your IP address, but still leaves your browser info available to the website because the website "needs" that information to customize their service so it displays correctly.
They’ve gotten it somehow and sold it multiple times to multiple people. There is no escaping it.