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# 使用 Amazon Chime SDK PSTN 音频服务接收来电者输入
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您可以使用 `ReceiveDigits` 操作收集入站 DTMF 数字并将其与正则表达式进行匹配。当 SIP 媒体应用程序收到与正则表达式匹配的数字时，它会调用带有`ACTION_SUCCESSFUL`事件的 AWS Lambda 函数。收集的数字显示在 `ActionData` 对象的 `ReceivedDigits` 值中。

例如：

```
{
    "SchemaVersion": "1.0",
    "Sequence": 4,
    "InvocationEventType": "ACTION_SUCCESSFUL",
    "ActionData": {
        "ReceivedDigits": "",
        "Type": "ReceiveDigits",
        "Parameters": {
            "CallId": "call-id-1",
            "InputDigitsRegex": "^\d{2}#$",
            "InBetweenDigitsDurationInMilliseconds": 5000,
            "FlushDigitsDurationInMilliseconds": 10000
        }
    },
    "CallDetails": {
        "TransactionId": "transaction-id",
        "AwsAccountId": "aws-account-id",
        "AwsRegion": "us-east-1",
        "SipRuleId": "sip-rule-id",
        "SipApplicationId": "sip-application-id",
        "Participants": [
            {
                "CallId": "call-id-1",
                "ParticipantTag": "LEG-A",
                "To": "+12065551212",
                "From": "+15105550101",
                "Direction": "Inbound",
                "StartTimeInMilliseconds": "159700958834234",
                "Status": "Connected"
            }
        ]
    }
}
```

一旦呼叫者输入与您的正则表达式模式相匹配的数字，SIP 媒体应用程序就会调用一个 AWS Lambda 函数，返回以下类型的有效负载：

```
{
    "SchemaVersion": "1.0",
    "Sequence": 5,
    "InvocationEventType": "DIGITS_RECEIVED",
    "ActionData": {
        "ReceivedDigits": "11#",
        "Type": "ReceiveDigits",
        "Parameters": {
            "CallId": "call-id-1",
            "InputDigitsRegex": "^\d{2}#$",
            "InBetweenDigitsDurationInMilliseconds": 5000,
            "FlushDigitsDurationInMilliseconds": 10000
        }
    },
    "CallDetails": {
        "TransactionId": "transaction-id",
        "AwsAccountId": "aws-account-id",
        "AwsRegion": "us-east-1",
        "SipRuleId": "sip-rule-id",
        "SipApplicationId": "sip-application-id",
        "Participants": [
            {
                "CallId": "call-id-1",
                "ParticipantTag": "LEG-A",
                "To": "+12065551212",
                "From": "+15105550101",
                "Direction": "Inbound",
                "StartTimeInMilliseconds": "159700958834234",
                "Status": "Connected"
            }
        ]
    }
}
```

参见工作示例 GitHub：[https://github.com/aws-samples/amazon-chime-sma-on-demand-](https://github.com/aws-samples/amazon-chime-sma-on-demand-recording) recording