Rate limiting is caused by any of the following conditions:
A bot sends messages too frequently
A client of a bot sends messages too frequently
Direct Line clients request a new Web Socket too frequently
How to implement human handoff?
At times it is necessary to transfer (handoff) a conversation from a bot to a human being. This happens for example if the bot does not understand the user, or if the request cannot be automated. In these cases, the bot provides a transition to humans. The Bot Framework SDK supports handoff to a human. There a few event types for signaling handoff operations. These events are exchanged between a bot and an agent hub, also called engagement hub. This agent hub is defined as an application or a system that allows agents, typically humans, to receive and handle requests from users, as well as escalation requests from bots