The eco-taxi-only app "Eco-Taxi" with a cheap Kanto rate (first ride 310 yen, pick-up fee 290 yen, no late-night surcharge, long-distance 3-step discount) allows eco-taxi users to call the dispatch room one by one. It is a convenient application that allows you to display a map on your smartphone and pinpoint the position you want to ride.
Even if you are in the room, you can call where you want to board.
What's more, you only have to get out on the road at the same time as the car arrives, and you don't have to wait for the car or wait for it.