Linphone is getting a full internationalization support, using Transifex platform.
Currently Linphone Desktop, Linphone Android and Linphone iOS are using Transifex. Linphone Web and Linphone Windows Phone are coming soon.
Linphone is almost 100% translated in English, French, Arabic, Japanese, German and Russian thanks to devoted contributors!
You can contribute at : https://www.transifex.com/organization/belledonne-communications