iOS devices – is all about enhancing the experience for users while they are actually talking on their phones. Specifically, the free app lets users share video, photos and other data in real time with others while they are on the line. Beyond serving as a business or virtual meeting application, the purpose of Sidecar is to let people share the spontaneity of life’s experiences in real time.

“You may never want to share spreadsheets on the call,” Williams said. “But you do want to see the smile on a kid’s face.”

Here is a glimpse of how Sidecar actually works.

Free calls for everyone

Unlike other apps which enable free or substantially cheaper phone calls over Internet connections, but limit calls to recipients who also have the app installed, Sidecar enables users to make calls to anyone in the U.S. or Canada over a wireless network. The ability to share added media, of course, does require that both users have the app installed. If you are calling over a 3G or 4G network, carrier rates will apply.

Sidecar is the second service launched by Williams’ company, which he co-founded with RealNetworks founder Rob Glaser. The company, which has 10 employees based in offices in Seattle and San Francisco, previously tried a Facebook-enabled video conferencing service called SocialEyes.

“SocialEyes wasn’t able to work across web and mobile,” Williams said. “It’s very hard to build a great mobile experience that is also a great web experience. We realized we couldn’t be both and we chose mobile.”

Williams added that his team is focused on refining Sidecar and generating a critical mass of users before investing time in monetization, which will eventually be done through premium services. The company is backed by Seattle-based Ignition Partners.

A tale of two platforms

While Williams and Glaser have a deep history with Microsoft, making Sidecar accessible to Windows-enabled smartphones upon launch was never really a consideration.

“The opportunity costs prevent entrepreneurs from focusing beyond Android and iOS right now,” Williams said. “I’d love it if Microsoft manages to make Windows a bigger part of the market. It’s up to them and not me.”

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