Google Hangouts vs Jami (formerly GNU Ring, SFLphone)

Hangouts offers both an Android and iOS app so users can participate from nearly any mobile device in addition to his Desktop.

Any user can share his screen (or only a specific desktop or window) while still continuing an audio conversation.

Hangouts works with up to 10 participants using video out of the box or up to 15 if you are a business, government or school. It determines who is the primary speaker at any given time, and the camera view automatically switches to that user.

Hangouts is integrated with Gmail & Google+, does not require you to download desktop software, and all chats can take place directly in your browser, significantly reducing the barrier to entry for a new user.

Google offers all features of Hangouts completely free. There are business, education and government solutions that increase the participant count to for video calls to 15 and offers support.

Hangouts work on Android, iOS, Chrome OS, web and as a Chrome extension.

Hangouts can scale to become a videoconferencing solution for an entire company, since the software can run on nearly all platforms. In fact, Google itself uses Hangouts as its meeting room video conference software.

With Google+ “Hangouts on Air”, you can broadcast any hangout to an unlimited audience via your Goolge+ Profile or simply a generic YouTube link. Moreover, any Hangout on Air (public or private) is automatically saved as YouTube video that you can keep for private reference or use in any way that you would normally share a YouTube video. This allows you to record conversations without additional obtrusive software.

Allows for a fixed phone number, receiving and making calls. Calling US or Canada is free.

When chatting with people while trying to plan a meet up, the share map button can be extremely useful.

Contribute to and/or audit the source code here.

Make audio and video calls with multiple people on Jami. Easily add new participants. Because Jami does not rely on servers, the conference is hosted by the device of the person who initiates it. It mixes the audio and video feeds from all the participants and sends it back to them so everyone can see and hear each other. For this reason, the maximum number of participants depends on the hosting device's computing power and available bandwidth. The developers have tested video conferencing with up to sixteen members; however, it could potentially go higher.

You can change the source of the video feed you send your friends during a call, allowing you to share either your entire screen or only sections. You can also stream any audio and video media files, allowing your friends to see or hear them without having to transfer them first. This is accessed by right-clicking on the screen during a call.

If your device has a 4K camera, you can use it to its full potential with Jami thanks to the support for Ultra HD resolution. It is only really useful if the other person has a 4K screen, but if it's the case, they will see you as clearly as if you were there.

Record and send audio and video messages. This is convenient for when you want to send a quick message without typing.

Active community with frequent articles posted on their blog.

Calls have crystal clear audio.

If required, works within a Local Area Network (LAN) without the need for an Internet connection.

The Jami software has many features and is stable; yet, the rate of development is increasing as more developers are contributing to provide even more features while keeping the software stable.
https://git.jami.net/

If there is a wired and/or wireless connection between the caller and receiver, you can make a call.

Translated into many languages and open for more translations.
https://www.transifex.com/savoirfairelinux/jami/

Answer and make VoIP telephone calls from anywhere in the world where you are connected to the internet.

The same account can be setup on multiple devices. You can then make calls between the same account on different devices. You can also transfer files between devices without using third-party services (like email accounts).

Send files of all sizes between Jami users. FLAC, GIF, JPEG, JPG, MKV, MP3, MP4, OGG, PNG, WAV, WEBM and WEBP file extensions are automatically downloaded.

Works with devices running Android, Android TV, GNU/Linux, iOS, macOS and Windows operating systems.

You can have multiple Jami and SIP accounts active concurrently.