Hello,

I need to design an application to introduce cwc using DMCC APIs. Would you please tell me what is the right scenario for introducing a CWC code?

From documentation:
To use CWCs, an agent must be:

On an ACD call.
A manual-in agent in the After Call Work (ACW) mode.
An auto-in agent in the Pending for ACW or Timed ACW mode.

However, it is not clear for me if the call needs to be canceled or not in order to introduce the code.
Or the call state is not important, only agent state (ACW)?

I am not sure what you mean by canceled (I am assuming disconnected/dropped/hung-up).
I feel the answer to your question is in the feature description already.

1. On an ACD call (the call is active)
2. A manual-in agent in the After Call Work (ACW) mode (the call has ended).
3. An auto-in agent in the Pending for ACW (the call is active but is in the pending for ACW state) or Timed ACW mode (the call has ended).

In the feature description
https://documentation.avaya.com/bundle/CCEliteFeatureReference_r81x/page/CallWorkCodes.html

If you read all of it, it is clear that CWC can be entered while the agent is on a call with a customer.
"The agent waits for a ready indication or the caller hears the touchtone digits."
"If the agent presses a button or releases the call during digit collection, Communication Manager cancels the CWC entry, turns off the lamp indicator, and clears the phone display."

Thanks.
Yes, all the tests have been performed while being on the call ( acd call, agent set to ACW ). Works okay.

However, customer needs to know if it is possible to send CWC digits after disconnecting the call, so I was not sure if this scenario is supported as per doc.

CWC can be entered only if the agent is in After Call Work mode.