They - Grubhub not Yelp - record every phone call, as the article points out, and even make it available to the restaurants, with personal details censored (unless of course their algorithms fuck up, and it does fuck up).

So chances are if you ever called via Yelp into one of such Grubhub numbers, they got at least your voice and your food preferences (which might include medical/dietary needs) on record, maybe even your full details and CC number etc (depending on the quality of their automated censoring algorithms and on whether or not they store the original unredacted calls as well).

“This call may be recorded to ensure awesomeness”, as their phone robot tells you :P

They are listening in on the phone call.