I forgot to mention - we too (the parents) have been using hand-me-down phones for years now on pay as you go service. As our kids swapped their dumb phones for smart phones we just took over the service at the minimum rate until the contracts ran out and switched them over to "Pay as you GO".
We only use them when out and only answer the calls on our Favourite 5 plan.
We don't text or hold lengthy conversation on these. That's what a home line is for.