Starting tomorrow, people in New York City and Philadelphia with iOS devices will be able to access ABC’s entire network schedule live online, as the broadcaster tests out a new cloud-based service intended to compete with Aereo and others.

This would make ABC the first of the major broadcast networks to make all of its programming available live online. Networks have been experimenting with the idea for years — and NBC has streamed much of its Olympics coverage live for the last two games — but networks shows have generally only been available for online viewing either on each network’s website, or services like Hulu and Netflix… or Aereo, the subjects of lawsuits filed by the broadcasters.

Startup service Aereo charges users a monthly fee to be able to watch over-the-air network feeds online. The networks claim Aereo is illegally rebroadcasting their signals without permission or paying a fee, while Aereo contends that its use of tiny antennae — each dedicated to a single customer — means it is doing nothing more than transmitting legally collected broadcasts to the user of each antenna.

While CBS and News Corp (parent company of FOX) have each indicated they may go cable-only if they fail in their bid to stop Aereo, the ABC tactic is a less drastic approach, giving viewers a reason to not sign up for Aereo in the first place.

The initial 6-week test in New York and Philadelphia will be available to anyone. After that, users will need to show they are subscribers to a participating cable service. ABC hopes to extend the streaming service to other markets where the affiliate is network-owned.

The requirement to be a cable subscriber takes some of the wind out of the service’s “anti-Aereo” sail, as that service is targeted to subscribers looking to cut the cable cord and go online-only.

GigaOm’s Janko Roettgers gets into the various technical ways in which ABC’s cloud-based service should be easier and less expensive to roll out than Aereo, but it basically comes down to new technology that allows ABC to swap out commercials and programming on the fly, depending on the availability of rights and each affiliate’s schedule.

But of course, points out Roettgers, since Aereo is simply sending out whatever the antenna picks up, it doesn’t need to worry about such nuances, and the end-user will receive exactly what’s being shown on TV.

Mashable reports that ABC intends to have an Android version of the Watch ABC app available later this summer for Samsung Galaxy devices.

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