What is a String Identifier (SID)?

A String Identifier (SID) is a unique key that identifies specific resources.

String Identifiers at Twilio

Every Twilio resource has a 34 character SID. You can use the first two characters of the SID to identify its type. For example, Call resource SIDs begin with the letters CA, and Message resources begin with MM. The remaining 32 characters of the SID are digits.

Many API calls to Twilio return a JSON object containing a resource's SID. Using this SID, you can retrieve more information about the specific resource.

For example, the following code creates an SMS message:

Create a new text message

1// Download the helper library from https://www.twilio.com/docs/node/install
2const twilio = require("twilio"); // Or, for ESM: import twilio from "twilio";
3
4// Find your Account SID and Auth Token at twilio.com/console
5// and set the environment variables. See http://twil.io/secure
6const accountSid = process.env.TWILIO_ACCOUNT_SID;
7const authToken = process.env.TWILIO_AUTH_TOKEN;
8const client = twilio(accountSid, authToken);
9
10async function createMessage() {
11  const message = await client.messages.create({
12    body: "This will be the body of the new message!",
13    from: "+14155552344",
14    to: "+14155552345",
15  });
16
17  console.log(message.sid);
18}
19
20createMessage();

Response

1{
2  "account_sid": "ACaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
3  "api_version": "2010-04-01",
4  "body": "This will be the body of the new message!",
5  "date_created": "Thu, 24 Aug 2023 05:01:45 +0000",
6  "date_sent": "Thu, 24 Aug 2023 05:01:45 +0000",
7  "date_updated": "Thu, 24 Aug 2023 05:01:45 +0000",
8  "direction": "outbound-api",
9  "error_code": null,
10  "error_message": null,
11  "from": "+14155552344",
12  "num_media": "0",
13  "num_segments": "1",
14  "price": null,
15  "price_unit": null,
16  "messaging_service_sid": "MGaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
17  "sid": "SMaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
18  "status": "queued",
19  "subresource_uris": {
20    "media": "/2010-04-01/Accounts/ACaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/Messages/SMaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/Media.json"
21  },
22  "tags": {
23    "campaign_name": "Spring Sale 2022",
24    "message_type": "cart_abandoned"
25  },
26  "to": "+14155552345",
27  "uri": "/2010-04-01/Accounts/ACaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/Messages/SMaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.json"
28}

The JSON response to this API call from Twilio has a property named sid. Using this value, you can later fetch this specific message that you created.

Fetch a Message by SID

1// Download the helper library from https://www.twilio.com/docs/node/install
2const twilio = require("twilio"); // Or, for ESM: import twilio from "twilio";
3
4// Find your Account SID and Auth Token at twilio.com/console
5// and set the environment variables. See http://twil.io/secure
6const accountSid = process.env.TWILIO_ACCOUNT_SID;
7const authToken = process.env.TWILIO_AUTH_TOKEN;
8const client = twilio(accountSid, authToken);
9
10async function fetchMessage() {
11  const message = await client
12    .messages("SMaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
13    .fetch();
14
15  console.log(message.status);
16}
17
18fetchMessage();

Response

1{
2  "account_sid": "ACaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
3  "api_version": "2010-04-01",
4  "body": "testing",
5  "date_created": "Fri, 24 May 2019 17:18:27 +0000",
6  "date_sent": "Fri, 24 May 2019 17:18:28 +0000",
7  "date_updated": "Fri, 24 May 2019 17:18:28 +0000",
8  "direction": "outbound-api",
9  "error_code": 30007,
10  "error_message": "Carrier violation",
11  "from": "+12019235161",
12  "messaging_service_sid": "MGaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
13  "num_media": "0",
14  "num_segments": "1",
15  "price": "-0.00750",
16  "price_unit": "USD",
17  "sid": "SMaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
18  "status": "sent",
19  "subresource_uris": {
20    "media": "/2010-04-01/Accounts/ACaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/Messages/SMb7c0a2ce80504485a6f653a7110836f5/Media.json",
21    "feedback": "/2010-04-01/Accounts/ACaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/Messages/SMb7c0a2ce80504485a6f653a7110836f5/Feedback.json"
22  },
23  "tags": {
24    "campaign_name": "Spring Sale 2022",
25    "message_type": "cart_abandoned"
26  },
27  "to": "+18182008801",
28  "uri": "/2010-04-01/Accounts/ACaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/Messages/SMb7c0a2ce80504485a6f653a7110836f5.json"
29}

Using the message SID, which is prefixed with MM, you were able to get more information about that specific resource.