TwiML™ for Programmable Voice

TwiMLとは何か

TwiML (the Twilio Markup Language) is a set of instructions you can use to tell Twilio what to do when you receive an incoming call, SMS, or fax.

How TwiML works

When someone makes a call to one of your Twilio numbers, Twilio looks up the URL associated with that phone number and sends it a request. Twilio then reads the TwiML instructions hosted at that URL to determine what to do, whether it's recording the call, playing a message for the caller, or prompting the caller to press digits on their keypad.

At its core, TwiML is an XML document with special tags defined by Twilio to help you build your Programmable Voice application.

The following will say "Hello, world!" when someone dials a Twilio number configured with this TwiML:

You can always return raw TwiML from your language of choice, or leverage the Twilio helper libraries to automatically create valid TwiML for you. In the code sample below, toggle to your preferred web programming language to see how the above TwiML looks using the helper library.

Outbound calls (calls from a Twilio number to an outside number) are controlled using TwiML in the same manner. When you initiate an outbound call with the Twilio API, Twilio then requests your TwiML to learn how to handle the call.

Twilio executes just one TwiML document to the caller at a time, but many TwiML documents can be linked together to build complex interactive voice applications.

TwiML elements

In TwiML parlance, XML elements are divided into three groups: the root <Response> element, verbs, and nouns.

You can use XML comments freely in your TwiML; the interpreter ignores them.

<Response> 要素

In any TwiML response to a Twilio request, you must nest all verb elements within <Response>, the root element of Twilio's XML markup:

<?xml version="1.0" encoding="UTF-8"?>
<Response>
    <Say>
      This message must be nested in a Response element
      in order for Twilio to say it to your caller.
    </Say>
</Response>

他のいかなる構造も無効とみなされます。

TwiML verbs for Programmable Voice

TwiML verbs tell Twilio what actions to take on a given call. Because of this, most elements in a TwiML document are TwiML verbs. Verb names are case sensitive, as are their attribute names.

You can use different combinations of TwiML verbs to create all kinds of interactive voice applications. The core TwiML verbs for Programmable Voice are:

• <Say> - Read text to the caller
• <Play> - Play an audio file for the caller
• <Dial> - Add another party to the call
• <Record> - Record the caller's voice
• <Gather> - Collect digits the caller types on their keypad

The following verbs may be used to control the flow of your call:

• <Hangup> - Hang up the call
• <Enqueue> - Add the caller to a queue of callers
• <Leave> - Remove a caller from a queue of callers
• <Pause> - Wait before executing more instructions
• <Redirect> - Redirect call flow to a different TwiML document
• <Refer> - Twilio initiates SIP REFER towards IP communication infrastructure
• <Reject> - Decline an incoming call without being billed

The following nouns provide advanced capabilities:

• <Autopilot> - Build AI-powered Conversational IVR

For example, if a <Say> verb is followed by a <Redirect> and then another <Say>, the 2nd <Say> is unreachable because <Redirect> transfers full control of a call to the TwiML at a different URL.

TwiML名詞

A TwiML noun describes the phone numbers and API resources you want to take action on. Effectively, a TwiML noun is anything nested inside a verb that is not itself a verb: it's whatever the verb is acting on.

TwiML nouns are usually just text. However, as in the case of <Dial> with its <Number> and <Conference> nouns, at times there are nested XML elements that are nouns.

開発者のアプリケーションへのTwilioからのリクエスト

When someone makes an inbound call to one of your Twilio phone numbers, Twilio needs to request TwiML from your application to get instructions for handling the call.

You can configure your Twilio phone number to point to your application's URL by visiting the phone numbers section of the console. Select your phone number, then scroll to the 'Voice & Fax' section to set a webhook, TwiML bin, or Twilio Function for Twilio to send that HTTP request when a call comes in:

Twilio makes its request over HTTP, either as a GET or POST, just like requesting a web page in your browser or submitting a form.

By including parameters and values in its request, Twilio sends data to your application that you can act upon before responding.

リクエストパラメーター

Twilio always sends the following parameters with its request.

These will send as either POST parameters or URL query parameters, depending on which HTTP method you've configured.

Twilio also attempts to look up geographic data based on the To and From phone numbers. If available, Twilio will send the following parameters with its request:

通話中に起こったことに応じて、他の変数も送信されることがあります。

For example, when Twilio receives SIP, it will send additional parameters to your web application: you'll find the list of parameters sent with SIP in "SIP and TwiML interaction".

CallStatus 値

The following are the possible values for the CallStatus parameter. These values also apply to the DialCallStatus parameter, which is sent with HTTP requests to a <Dial> action URL.

Ending the call: callback requests

After receiving a call, requesting TwiML from your app, processing it, and finally ending the call, Twilio will make an asynchronous HTTP request to the StatusCallback URL configured for the Twilio number that was called.

You need to explicitly provide this URL to your application in the StatusCallback parameter of each message for which you want the status callbacks. The raw TwiML for this looks like:

The code sample below shows how to set your StatusCallback URL with plain TwiML or using the helper library of your choice:

By providing a StatusCallback URL for your Twilio number and capturing this request, you can determine when a call ends and receive information about the call. Please note that non-relative URLs must contain a valid hostname, and underscores are not permitted.

StatusCallback request parameters

When Twilio sends parameters to your application in an asynchronous request to the StatusCallback URL, they include the same parameters passed in a synchronous TwiML request.

この他にも、StatusCallback リクエストは次のパラメーターを渡します。

データフォーマット

電話番号

All phone numbers in requests from Twilio are in E.164 format if possible. For example, (231) 685-1234 would come through as '+12316851234'. However, there are occasionally cases where Twilio cannot normalize an incoming caller ID to E.164. In these situations, Twilio will report the raw caller ID string.

日付と時間

Twilio からのリクエストに含まれるすべての日付と時刻には、 RFC 2822 フォーマットの GMT 時間が使用されます。 たとえば、2010 年 8 月 19 日午後 6 時 13 分 (太平洋夏時間) は、「Fri, 20 Aug 2010 01:13:42 +0000」となります。

Twilioはお行儀のよいHTTPクライアントです

URL へ HTTP リクエストを送信する際、Twilio は通常のウェブ ブラウザと同じように振る舞います。

• Cookie: 通常のWebブラウザーと同様、TwilioはHTTP Cookieを受け入れ、これらを (Twilioからの) 各リクエストに追加します。
• リダイレクト: こちらも通常のWebブラウザーと同様、HTTPリダイレクト (HTTPステータスコード301、307、など) に従います。
• キャッシュ: こちらも通常のWebブラウザーと同様、HTTPヘッダーで許可されており (ETagおよびLast-Modifiedヘッダー) 、かつHTTPメソッドがGETである場合、Twilioはファイルのキャッシュを行います。

MIME Type に対応

Twilio はユーザー アプリケーションのレスポンスの MIME Type に応じて異なる動作をします。

Twilioにレスポンスを返す

In your response to Twilio's request to your configured URL, you can tell Twilio what to do on a call.

How the TwiML interpreter works

When your application responds to a Twilio request with XML, Twilio runs your document through the TwiML interpreter. To keep things simple, the TwiML interpreter only understands the few specially-named XML elements that make up TwiML: <Response>, verbs, and nouns.

The interpreter starts at the top of your TwiML document and executes instructions (verbs) in order from top to bottom.

The following code snippet reads "Hello World" to the caller before playing Cowbell.mp3 for the caller and then hanging up.

Just as with all TwiML, you can use the helper libraries to help you play some music to a caller. Include the loop attribute to tell Twilio to loop this recording 10 times (or until the caller hangs up):

Status callbacks in your response

ステータス・コールバックは通話フローを制御しないため、TwiMLを返す必要はありません。 レスポンスを返す際は、ステータスコード 204 No Content または、Content-Type: text/xmlおよび空の <Response/> のBodyをともなった 200 OK を使用してください。 正しくレスポンスを返さないと、デバッガーで警告が発生します。

関連トピック

Go in-depth to learn more about the various TwiML verbs you'll use with Twilio's Programmable Voice, such as <Dial> to connect a call or <Gather> for speech recognition and collecting user key presses. You'll find all in-depth reference documents linked above.

You may also wish to explore how to generate TwiML with Twilio's helper libraries, provided to let you generate TwiML in your favorite language.

For a guided walkthrough, check out our quickstarts that will show you how to make and receive phone calls with Twilio in C#/.NET, Java, Node.js, PHP, Python, or Ruby.