Build an SMS Responder

Copy

• Copy for LLM

  Copy page as Markdown for LLMs
• View as Markdown

  Open this page as Markdown
• Open in ChatGPT

  Get insights from ChatGPT
• Open in Claude

  Get insights from Claude
• Connect to Cursor

  Install MCP server on Cursor
• Connect to VS Code

  Install MCP server on VS Code

import type { FunctionContext } from '@sinch/functions-runtime';
import {
  ConversationController,
  getText,
  getChannel,
  getContactId,
} from '@sinch/functions-runtime';
import type { MessageInboundEvent } from '@sinch/functions-runtime';

class SmsHandler extends ConversationController {
  async handleMessageInbound(event: MessageInboundEvent): Promise<void> {
    const text = getText(event);
    if (!text) return;

    const channel = getChannel(event);
    const contactId = getContactId(event);
    console.log(`Inbound from ${channel}: "${text}" (contact: ${contactId})`);

    await this.conversation!.messages.send({
      sendMessageRequestBody: this.reply(event, `You said: ${text}`),
    });
  }
}

export async function setup(context: FunctionContext) {
  const handler = new SmsHandler(context.conversation, {
    CONVERSATION_APP_ID: context.env.CONVERSATION_APP_ID,
    FROM_NUMBER: context.env.FROM_NUMBER,
  });
  return handler.getWebhookHandler();
}

import {
  getText,
  getChannel,
  getContactId,
  getConversationId,
  getIdentity,
  getMedia,
  getPostbackData,
  isTextMessage,
  isMediaMessage,
  isPostback,
} from '@sinch/functions-runtime';

const text = getText(event); // 'Hello'
const channel = getChannel(event); // 'SMS', 'WHATSAPP', 'MESSENGER'
const contactId = getContactId(event); // Sinch contact ID
const identity = getIdentity(event); // Sender's phone/PSID/etc.

await this.conversation!.messages.send({
  sendMessageRequestBody: this.reply(event, 'Thanks for your message!'),
});

await this.conversation!.messages.send({
  sendMessageRequestBody: {
    app_id: this.config.CONVERSATION_APP_ID,
    recipient: { contact_id: contactId },
    message: { text_message: { text: 'A proactive message' } },
  },
});

await this.conversation!.messages.send({
  sendMessageRequestBody: {
    app_id: this.config.CONVERSATION_APP_ID,
    recipient: { contact_id: contactId },
    message: { text_message: { text: 'Reply via SMS' } },
    channel_priority_order: ['SMS'],
    channel_properties: {
      SMS_SENDER: this.config.FROM_NUMBER,
    },
  },
});

async handleMessageInbound(event: MessageInboundEvent): Promise<void> {
  const text = getText(event)?.trim().toUpperCase();
  if (!text) return;

  let reply: string;
  if (text === 'HELP') {
    reply = 'Text HOURS for our hours, or STOP to unsubscribe.';
  } else if (text === 'HOURS') {
    reply = 'We are open Monday through Friday, 9 AM to 5 PM EST.';
  } else if (text === 'STOP') {
    reply = 'You have been unsubscribed. Text START to re-subscribe.';
  } else {
    reply = 'Thanks for reaching out. Text HELP for available commands.';
  }

  await this.conversation!.messages.send({
    sendMessageRequestBody: this.reply(event, reply),
  });
}

async handleMessageInbound(event: MessageInboundEvent): Promise<void> {
  const channel = getChannel(event);
  const text = getText(event);

  if (channel === 'WHATSAPP') {
    await this.conversation!.messages.send({
      sendMessageRequestBody: this.reply(event, `WhatsApp: ${text}`),
    });
  } else if (channel === 'SMS') {
    const shortReply = (text ?? '').substring(0, 100);
    await this.conversation!.messages.send({
      sendMessageRequestBody: this.reply(event, shortReply),
    });
  } else {
    await this.conversation!.messages.send({
      sendMessageRequestBody: this.reply(event, `Got your message on ${channel}.`),
    });
  }
}