The phone number you use to send journal entries must be registered with your account. You can associate one (or more) phone numbers with your account in your profile settings here. If you try to send a journal entry using a non-registered phone number, it will not work.
Once you have a phone number setup, you must specify which journal text messages will be posted to. This is done by clicking on Settings for your phone number, picking the name of the journal from the list, and saving those settings.
Journal entries sent via text messaging will be posted using the default visibility settings for that journal. It is possible, however, to override those settings by including one or more of the following hashtags in the body of the message:
If any of these hashtags are found in a message, they will not be shown in the body of your journal entry.
To learn more about what these settings mean, please read our help section on Security and Privacy.