curl --request POST \
  --url https://api.sandbox.asapp.com/conversation/v1/conversations/{conversationId}/messages \
  --header 'Content-Type: application/json' \
  --header 'asapp-api-id: <api-key>' \
  --header 'asapp-api-secret: <api-key>' \
  --data '{
  "text": "Hello, I would like to upgrade my internet plan to GOLD.",
  "sender": {
    "role": "agent",
    "externalId": 123
  },
  "timestamp": "2021-11-23T12:13:14.555Z"
}'

{
  "id": "01BX5ZZKBKACTAV9WEVGEMMVS1"
}