This article is in need of a technical review.
This feature is not on a current W3C standards track, but it is supported on the Firefox OS platform. Although implementations may change in the future and it is not supported widely across browsers, it is suitable for use in code dedicated to Firefox OS apps.
voice is a read-only property that gives access to information about the voice connection.
var connection = navigator.mozMobileConnection.voice
Not part of any specification.