Under Settings - SMS, you can determine your SMS settings. You can view your balance, your sms log of most recently issued text messages and general settings for sending text messages.

SettingsHere you can enter your sender's name, the name displayed on the recipient's phone when they receive a text message from your account. You can either choose a text of up to 11 characters or a phone number. If you use a text, your text messages can not be answered.
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You can also grant permission for your group managers and supervisors to send text messages.

This is also where you can set whether your users should be reminded of upcoming SMS sms and when this reminder should occur.