Click-to-Call and StarLeaf Cloud
Managing Cloud StarLeaf Cloud and traffic routing for administratorsLast updated June 28, 2018
StarLeaf Cloud allows for video calling to take place within a web browser. We call this Click-to-Call. Video calling within a browser is sometimes known as WebRTC (Web Real-Time Communication).
People who want to join a StarLeaf conference (and who do not have their own video equipment) can use Click-to-Call to do so.
- Anyone can now directly dial in to a StarLeaf conference from their web browser, simply by clicking a link
- Anyone can now directly call any StarLeaf Cloud endpoint from their web browser. This includes StarLeaf room systems, StarLeaf desktops, StarLeaf Breeze, and any H.323 or SIP endpoint that is registered to the StarLeaf Cloud
Guest invites include a link to call the person who sent the invite point-to-point from a web browser.
If you are a StarLeaf user, you can include a link in your email signature (or elsewhere) that launches a browser ready to call you.
You can also create links to allow video calls to anyone in your organization from your web sites or applications. For more information, refer to Browser Click-to-Call links.
To use Click-to-Call, video callers need at least:
- Chrome 46
- Internet Explorer 11 (requires add-in)
- Safari 9 (requires add-in)
- Firefox 55
For best support and compatibility, StarLeaf recommends using Chrome or Internet Explorer for Click-to-Call.
Browsers running on iOS (iPhone and iPad) do not support any WebRTC. Therefore, you cannot use Click-to-Call on these devices.
Chrome users do not need a add-in to use Click-to-Call, but they need a to install an extension if they will share their screens whilst using Click-to-Call.
To be able to share your screen from Chrome, you will be prompted to use the Screen Share for StarLeaf Click-to-Call extension. Chrome users can find the add-in here: https://chrome.google.com/webstore/detail/screen-share-for-starleaf/dliccfbpegdcmlflaidhhnloeofgdnce .
Internet Explorer users will be prompted by their browser to download the StarLeaf Browser Add-in when they load the Click-to-Call page in their browser. This enables the browser to use Click-to-Call and also use screen share.
Safari users will be prompted by their browser to download the StarLeaf Browser Add-in when they load the Click-to-Call page in their browser. This enables the browser to use Click-to-Call and also use screen share.
If you are using the Safari browser on macOS, you may encounter issues with the Mac feature AppNap. This feature puts apps to sleep if they are running in the background and aren’t visible to you, and includes individual Safari tabs. If you minimize a window while Click-to-Call is active, the call is unable to respond until you bring it to the foreground again.
This does not prevent you from using Click-to-Call but may cause difficulties in screen sharing situations where other participants in the call are sharing content. When AppNap has put the tab with the call to sleep, the request to start a screen share times out and you are dropped from the call. StarLeaf recommends that if you are using Click-to-Call in Safari and on macOS, you keep the Safari tab with the call in the foreground if at all possible.
As an alternative, you can use the Chrome browser or disable AppNap. If you choose to disable the AppNap feature, be aware that your battery life will be effected.
From Firefox version 59, the ability to share your screen using Click-to-Call is no longer supported. StarLeaf no longer recommends using Firefox with Click-to-Call.
Users of StarLeaf Click-to-Call browser video calling can share their screen with the person or conference at the other end of the call.
The picture below shows a browser-based call with shared content.
StarLeaf browser-based video calling does not require UDP ports to be open on your firewall; however, StarLeaf calls prefer to use UDP if possible because that provides superior call quality.
The use of TCP ports allows:
- successful browser-based calling even where there is a corporate firewall that is configured to block UDP traffic
- better performance where there is limited bandwidth
Firefox users must have access to UDP as, currently, Firefox browser calling does not work with TCP port 443.
To find more information about ports used by Click -to-Call, refer to Firewall configuration for StarLeaf endpoints.
For StarLeaf browser-based (WebRTC) calling, the call signaling uses TLS authentication and encryption. The media stream is encrypted using SRTP. During call signaling, the StarLeaf Cloud shares a DTLS fingerprint using TLS signaling. This fingerprint is used to set up a secure DTLS connection for the media.
StarLeaf Click-to-Call uses dynamic bandwidth. This effectively prevents video browser calls from overusing your Internet connection. Where you have low or fluctuating bandwidth, Click-to-Call automatically and dynamically adjusts bandwidth use to avoid packet loss.
Dynamic bandwidth support also means that where there are good network conditions with high bandwidth availability, Click-to-Call will scale up resolution and provide a much better video experience.
The dynamic bandwidth algorithm used by Click-to-Call is designed by Google, and this is implemented in all browsers we support. For more information about that algorithm, refer to A Google Congestion Control Algorithm for Real-Time Communication on the WWW .
Click-to-Call supports connections through proxies that support the use of HTTP CONNECT on port 443. The StarLeaf Cloud uses HTTP CONNECT to open an end-to-end TCP connection between the browser and the StarLeaf Cloud Border Controller. Click-to-Call will use the proxy settings that are configured in the user’s browser settings.
The proxy must allow connections to <subdomain>.call.sl.