If you use Google's browser, Chrome, then you can install the "Chat for Google" extension.
Beside installing the "extension" through the Google Chrome Web Store it requires no configuration because it automatically signs you in unless you're already signed into your Google Account.
It only runs while Chrome is running, which is disappointing, so if you close Chrome that service will quit as well. But if you use Chrome as your primary browser I suppose that doesn't matter.
Also, it displays a window of contacts from your Google account, acting as a chat service. You can close the contacts list, but I'm not sure if you can silent the incoming chats (which is desirable if you use Messages for your chat client).
I happily receive and dial calls from the application though!