Bug 977588 - [Dialer] The Active call screen does not have the option to place calls on hold.

@pacorampas : If the button you are providing the text for is an icon you should just use either:
* aira-label attribute with the localized text as a value on the button itself (simplest)
* or, as @DouglasSherk mentioned, aria-labelledby attribute with the id of the text node as a value (however if the text node is there only to be used as a label use the first option)
Hope this helps.