Bug 833229 - 1/N: rename VoicemailProvider to VoicemailService
Bug 833229 - 2/N: remove voicemail related lines in RILContentHelper.js
Bug 833229 - 3/N: build voicemail by default
Bug 833229 - 4/N: interface changes
Bug 833229 - 5/N: add voicemail module