Agents with the appropriate user rights are able to initiate standalone SMS messages from within the DTA. (A standalone SMS message is one initiated by the agent as the first in a conversation, rather than as a response to message received.) You are able to control which CLIs agents can assign to such messages by defining permitted CLIs and then assigning them to agent groups. When an agent then initiates a standalone SMS message from within the DTA, they are able to select the CLI to use from those assigned to the agent groups to which they belong.
Each CLI can be up 11 (alphanumeric) characters long. Any spaces at the start or end of the CLI are removed.