"Even though restaurants are capable of taking orders directly—after all, both numbers are routed to the same place—Yelp is pushing customers to Grubhub-owned phone numbers in order to facilitate what Grubhub calls a “referral fee” of between 15 percent and 20 percent of the order total, I learned while researching an episode for the podcast Underunderstood.
Yelp has historically functioned like an enhanced Yellow Pages, listing direct phone numbers for restaurants along with photos, information about the space, menus, and user reviews. But Yelp began prompting customers to call Grubhub phone numbers in October 2018 after the two companies announced a “long-term partnership.”"
https://www.vice.com/en_us/article/wjwebw/yelp-is-sneakily-replacing-restaurants-phone-numbers-so-grubhub-can-take-a-cut
Yelp has historically functioned like an enhanced Yellow Pages, listing direct phone numbers for restaurants along with photos, information about the space, menus, and user reviews. But Yelp began prompting customers to call Grubhub phone numbers in October 2018 after the two companies announced a “long-term partnership.”"
https://www.vice.com/en_us/article/wjwebw/yelp-is-sneakily-replacing-restaurants-phone-numbers-so-grubhub-can-take-a-cut