Pressing buttons on incoming phone calls

It may depend specifically on the call but I'm not familiar with any scams that do that. Most either will note that the phone number is active and add the list to phone numbers to sell to other scammers, or it'll connect them to a scammer calling with one of those many scams where they pretend to be Microsoft, Amazon, Apple, etc.

If they have Telus as their phone service provider, I would suggest enabling Call Control. It will block any call where there isn't a human present. 

Telus Mobility: https://www.telus.com/en/support/article/call-control-for-mobile-devices-explained

Telus Landline: https://www.telus.com/en/support/article/call-control-explained