If the driver is close enough that you can talk to him, your question would work. Or you could ask: Are you ready for a fare? If there are several drivers together at a cab stand, they probably have a system where they take turns. You could ask: Who's first? OR Who's next in line? If you see a taxi going by, you can "hail a cab" by waving your arm to get the driver's attention to try to get him to stop. In many cities, you can call the taxi company to speak with a dispatcher who sends cabs to the people who call: dispatcher: XYZ taxi. you: Hi, I need a cab at _____. (Give them your exact address or location.) In some cities, there may be a centralized app for getting cab rides from multiple companies-- or one or more companies may have their own app. Or as Anton said, you can also use a rideshare app in most cities.

Hmm, to order it in Uber or Yandex.Go?

Taxi 🙋🏻‍♂️🤠