Voice posts were previously made by using your phone to record a message, and the recording was posted as an entry to your journal. Voice posts can still be listed to and transcribed, but the feature has been discontinued and it is no longer possible to make new voice posts.
Paid, Permanent and Plus users can post by email or text message. On your Mobile Post Settings page, start by setting an allowed sender address and an authentication method (PIN, PGP or GPG public key).
LiveJournal offers mobile apps for iPhones/iOS, Android, Windows Phone, and Windows Mobile. There are also third party apps developed for LiveJournal that allow you to use many of LiveJournal's features without opening your web browser.