When you send a message to the LINE channel via the Conversation API, we will respond to your webhook with a delivery receipt if your Conversation API "app" has subscribed to the MESSAGE_DELIVERY triggers.
When the delivery receipt returns a 429 error, it will include the description
"code": "CHANNEL_FAILURE",
"description": "Line Error Code description: Exceeded the rate limit for requests,
Line status message: You have reached your monthly limit."
This means that you have reached your monthly quota and you need to wait until 1st of next month or go to your LINE account and upgrade your plan.
We recommend that you read the article: Is there a limit on the number of messages I can send with LINE? to understand more about the monthly quota.
It is also possible that you received the same error code 429 when you have sent too many requests at the same time. In such a case, you will need to slow down with your requests.
The Sinch Developer Documentation site contains comprehensive documentation and tutorials, which show you how we support LINE through the Sinch Conversation API.
