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Anyone who will be sending SMS into the system will need to be registered in CommConnect. Their numbers have to belong to a contact in your domain, otherwise, their messages can't be tied down to your domain and they won't show up in the message log. For mobile workers, this means going through the phone registration workflow, and for cases you just have to set the right case properties and it does it automatically.
Note: If you encounter difficulties registering mobile workers, please check this link
Step 1 - Create an account with Telerivet
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