This add-on can only be used in conjunction with CalenGoo. It cannot be used without it. It is a very simple app that allows CalenGoo to dial phone numbers with extensions for conference calls. When installed, CalenGoo will automatically detect it and will highlight phone numbers including their extension.
The download of the app doesn't contain viruses or any kind of malware. Dominique Andre Gunia is the official developer of CG that can be found in the Productivity category. The tool was downloaded and installed by over 1K users and its latest stable update was on Aug 17, 2018.
On Google Play, this application is rated 3.8 by its users. Download the setup package of CG 1.3 that is completely free and take a look at users' reviews on Droid Informer. The app runs flawlessly on Android 4.0 and above.