Originally Posted by ls17031

I can now confirm that the machines accept credit cards. Besides purchasing 1 and 3 day passes, one can also top up an Opus card if they already have one. The only things that the machines do not sell are single-ride fares and "occasional" passes.

I would image that credit cards issued outside of Canada would work since the dip slot isn't chip-pin and we don't have that annoying "Please enter your zipcode..." feature in Canada.