Add voice call option to slim social app

Components

Slim social is a free Facebook open sourced client without advertising. It offers a very lightweight alternative to the official Facebook app.
The application is basically doing all that can be done official Facebook application, ie write on your wall or a friend's wall, see the photos of other users, manage groups, chat and so on but I noticed one important feature missing which is the ability to make voice call.

Proposal

The slim social offers the facebook services in a lightweight app which includes chatting, but the voice call option is surprisingly missing in the app. While chatting with the app, I wanted to place a voice call to my friend but found out its not included. I am proposing this option should be included.
Audio call is a very important part of chatting, and should not be missing in this great app.

Mockups / Examples

Image of the app without the feature

Here is an image of how the feature can be added to the app

Benefits

Voice call in the app will make user feel more convenient using the app without missing or being shortchanged of any of the feature of the original facebook app.
In conclusion, sometimes one might be too busy to sit back and start typing messages but the availability of voice call will make it more easy to communicate with fellow chatting members without wasting anytime.
Thanks