After configuring your channels, you must assign each of them to a channel group to allow agents to use Routing mode. By default, the platform creates two channel groups when Routing mode is enabled: Async and Realtime. (You can change these names, along with the rest of the settings.) If you like, you can add more channel groups to your account.
A channel group defines the default capacity and maximum capacity of any agent who is processing conversations from the channels included in that group.