That is the case. Only when the store is very busy will they have dedicated phone order takers. The rest of the time the drivers who are waiting for the next delivery, the pizza makers, and/or managers handle the phones.

Used to work at a Dominos, though it was pre-internet days. Not sure how much online business the typical store now gets, I know I still always call when I order pizza because it's faster than dealing with the website.

Annoyingly at Dominos they now also have an automated attendant answer the call initially, which reads off the daily specials. That's a big reason I don't often order Dominos anymore but instead call a competitor who still has live humans answering the phone.

When I was at Dominos we had a standard of no more than two rings before a person picked up. People would sprint across the store to get the phone before the third ring.