sends SMS message from Lambda using AWS SDK v3

lambda-sms.js

import { SNSClient, PublishCommand } from '@aws-sdk/client-sns'
const client = new SNSClient()

/**
 * Publish a message to a phone number
 * @param {string} number - phone number of recipient
 * @param {string} [message] - message to send to phone number
 * @returns {import('@aws-sdk/client-sns').PublishCommandOutput}
 */
async function publish(number, message) {
  /** @type {import('@aws-sdk/client-sns').PublishCommandInput} */
  const input = {
    PhoneNumber: number || '+5555555555',
    Message: message || 'SMS from Lambda!',
  }

  /** @type {import('@aws-sdk/client-sns').PublishCommand} */
  const command = new PublishCommand(input)
  const response = await client.send(command)
  return response
}

/**
 * @type {import('@types/aws-lambda').APIGatewayProxyHandler}
 */
export async function handler(event) {
  const { number, message } = event?.body || {}
  const response = await publish(number, message)
  return {
    statusCode: 200,
    body: JSON.stringify(response),
  }
}