When City Councilman Ben Kallos proposed a taxi-hailing app that would allow New Yorkers to summon yellow and green cabs from their phones, he hoped to help city-licensed taxis compete in a market increasingly impinged upon by ridesharing services like Uber and Lyft.

Ironically, his plan already has the support of at least one rideshare start-up, and it's the city's biggest cab drivers union, the New York Taxi Workers Alliance, that remains lukewarm on the proposal.

Some cities have banned apps that allow people to hail rides online. Kallos is suggesting an approach that's more carrot and less stick.

"Uber disrupted the marketplace," he says. "When you turn on your phone to hail a vehicle, if it works, you keep using it. And people want to be able to hail yellow-and-greens."

That's why Kallos proposed a bill in City Council in mid-December that would require the city's Taxi and Limousine Commission to create its own e-hailing app; cab drivers could choose to opt in and use the app if they wanted to pick up more riders. Along with the app, the TLC would also be asked to create an API, or application program interface, which would allow third-party apps to use the city's information on local cabs.