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# Platform Configuration -  SMS Delivery
Source: https://supertokens.com/docs/platform-configuration/sms-delivery

## Overview

SuperTokens sends SMS in different authentication scenarios.
The method applies to the `Passwordless` and `MFA` recipes.

The following page shows you how to configure the SMS delivery method and adjust the content that gets sent to your users.

## Delivery methods

### Default method

If you provide no configuration for SMS delivery, the backend SDK sends SMSs by talking to SuperTokens servers on `https://api.supertokens.com`.
This applies to both self hosted and managed services.

:::info Important
- This is a free service and is globally rate limited. This is not suitable for production use. If you do not receive an SMS using this method, then the SDK prints the SMS content on the terminal.
- We do not log / store any of the info sent to the API that sends out emails on behalf of your app.
- You cannot customize the SMS content when using this method. If you want to customize the content, please see one of the other methods in this section.
:::

### Twilio 

Using this method, you can provide your own Twilio account details to the backend SDK, and the SMS is sent using those.

<Tabs>
<Tab value="nodejs">

```tsx

supertokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        Passwordless.init({
            flowType: "USER_INPUT_CODE",
            contactMethod: "PHONE",
            // highlight-start
            smsDelivery: {
                service: new TwilioService({
                    twilioSettings: {
                        accountSid: "...",
                        authToken: "...",
                        opts: {
                            // optionally extra config to pass to Twilio client
                        },

                        // give either from or messagingServiceSid
                        from: "...",
                        messagingServiceSid: "...",
                    },
                })
            },
            // highlight-end
        }),
        Session.init()
    ]
});
```
</Tab>
<Tab value="go">

```go

supertokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        Passwordless.init({
            flowType: "USER_INPUT_CODE",
            contactMethod: "PHONE",
            // highlight-start
            smsDelivery: {
                service: new SupertokensService("<SMS API KEY GOES HERE>")
            },
            // highlight-end
        }),
        Session.init()
    ]
});
```
</Tab>
<Tab value="go">

```go

supertokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        Passwordless.init({
            flowType: "USER_INPUT_CODE",
            contactMethod: "PHONE",
            // highlight-start
            smsDelivery: {
                override: (originalImplementation) => {
                    return {
                        ...originalImplementation,
                        sendSms: async function ({
                            codeLifetime, // amount of time the code is alive for (in MS)
                            phoneNumber,
                            urlWithLinkCode, // magic link
                            userInputCode, // OTP
                        }) {
                            // TODO: create and send SMS
                        }
                    }
                }
            },
            // highlight-end
        }),
        Session.init()
    ]
});
```
</Tab>
<Tab value="go">

```go

supertokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        Passwordless.init({
            flowType: "USER_INPUT_CODE",
            contactMethod: "PHONE",
            smsDelivery: {
                service: new TwilioService({
                    // @ts-ignore
                    twilioSettings: { /*...*/ },
                    // highlight-start
                    override: (originalImplementation) => {
                        return {
                            ...originalImplementation,
                            getContent: async function ({
                                isFirstFactor,
                                codeLifetime, // amount of time the code is alive for (in MS)
                                phoneNumber,
                                urlWithLinkCode, // magic link
                                userInputCode, // OTP
                            }) {
                                if (isFirstFactor) {
                                    // send some custom SMS content
                                    return {
                                        toPhoneNumber: phoneNumber,
                                        body: "SMS BODY"
                                    }
                                } else {
                                    // for second factor, urlWithLinkCode will always be
                                    // undefined since we only support OTP based for second factor
                                    return {
                                        toPhoneNumber: phoneNumber,
                                        body: "SMS BODY"
                                    }
                                }

                                // You can even call the original implementation and
                                // modify its content:

                                /*let originalContent = await originalImplementation.getContent(input)
                                originalContent.body = "My custom body";
                                return originalContent;*/

                            }
                        }
                    }
                    // highlight-end
                })
            }
        }),
        Session.init()
    ]
});
```
</Tab>
<Tab value="go">

```go

supertokens.init({
    appInfo: {
        apiDomain: "...",
        appName: "...",
        websiteDomain: "..."
    },
    recipeList: [
        Passwordless.init({
            flowType: "USER_INPUT_CODE",
            contactMethod: "PHONE",
            // highlight-start
            smsDelivery: {
                override: (originalImplementation) => {
                    return {
                        ...originalImplementation,
                        sendSms: async function (input) {
                            // TODO: before sending SMS

                            await originalImplementation.sendSms(input)

                            // TODO: after sending SMS
                        }
                    }
                }
            },
            // highlight-end
        }),
        Session.init()
    ]
});
```
</Tab>
<Tab value="go">

```go