Send Typing Indicator <Badge>RCS</Badge>
Send a typing indicator from an RCS agent to a recipient.
This endpoint allows RCS agents to display a typing indicator to recipients. The indicator is a message bubble with animated typing dots like this: 
Use Case: Typing indicators are especially useful for providing feedback to users while the agent is thinking or generating a response that may take some time, creating a more engaging conversational experience.
Expiration: Typing indicators automatically expire after around 20 seconds or when the agent sends a message, whichever comes first.
Frequency: You can send typing indicators as many times as needed, though only one will be displayed at a time. Sending multiple typing indicators will extend the duration of the current indicator.
Note: Typing indicators are best-effort hints, not delivery-guaranteed state. The platform is allowed to coalesce or drop them, and the client UI decides when to show/hide.
Authentication
Request
The unique identifier of the RCS agent sending the typing indicator.
Format: agent_ followed by alphanumeric characters (e.g., agent_pinnacle).
The recipient's phone number in E.164 format.
Must include country code with a leading plus sign (e.g., +14155551234).
Response
Timestamp when the typing indicator was started (ISO 8601 format).
Timestamp when the typing indicator will automatically expire (ISO 8601 format).
This is typically one minute after startedAt unless a message is sent first.