In Cases database, under the tab Notes&Emails, user can find tab SMS/Text Msgs and send text message to a party(ies) or other entity(is). 

By clicking New SMS/Txt Msg new window opens. 

Selecting party and/or other entity from the list on the right side (that are related to the case), will automatically fill out fields to and SMS number. User can select multiple names. 

After clicking send, user will be notified if message was or was not sent. 

List in SMS/Text Msg will give user an overview of messages sent within a particular case.