Private channels allow you to create groups and topics for members. Channels can be used for different departments, projects, or teams. They can be used however you need to assist communication with your members. Organize topics and member so relevant information goes to to correct individuals. Private channels can only be seen by members who are invited. Completely separate from your SMS, private channels are for your internal communication purposes. Your messages will not affect your SMS count.
Messages sent in the channel will go to all members added. More members can be added by selecting the add member button in the top right of a selected channel. You can see the total number of members next to the channel name in the left column.