Responding to invocations with action lists using the Amazon Chime SDK PSTN audio service

You can respond to an AWS Lambda invocation event with a list of actions to run on the individual participants in a call. You can respond with a maximum of 10 actions for each AWS Lambda invocation, and you can invoke an AWS Lambda function 1,000 times per call.

By default, SIP media applications time out if a Lambda function doesn't respond after 20 seconds.

The following example shows the general response structure.

{
    "SchemaVersion": "1.0",
    "Actions": [        
        {
            "Type": "PlayAudio",
            "Parameters": {
                "ParticipantTag": "LEG-A",
                "AudioSource": {
                    "Type": "S3",
                    "BucketName": "bucket-name",
                    "Key": "audio-file.wav"
                }
            }
        },
        {
            "Type": "RecordAudio",
            "Parameters": {
                "DurationInSeconds": "10",
                "RecordingTerminators": ["#"],
                "RecordingDestination": {
                    "Type": "S3",
                    "BucketName": "bucket-name"
                }
            }
        }
    ]
}

When the AWS Lambda function returns the list of actions to the SIP media application, the following operations occur:

1. The application finishes running the current action on a call.

2. The application then replaces the old action set with a new set of actions received from the latest invocation event.

If the SIP media application receives a NULL action set, it keeps the existing actions.