GramJS

const { Api, TelegramClient } = require("telegram");
const { StringSession } = require("telegram/sessions");

const session = new StringSession(""); // You should put your string session here
const client = new TelegramClient(session, apiId, apiHash, {});

(async function run() {
  await client.connect(); // This assumes you have already authenticated with .start()

  const result = await client.invoke(
    new Api.account.SendChangePhoneCode({
      phoneNumber: "some string here",
      settings: new Api.CodeSettings({
        allowFlashcall: true,
        currentNumber: true,
        allowAppHash: true,
        allowMissedCall: true,
        logoutTokens: [Buffer.from("arbitrary data here")],
      }),
    })
  );
  console.log(result); // prints the result
})();

import { Api, TelegramClient } from "telegram";
import { StringSession } from "telegram/sessions";

const session = new StringSession(""); // You should put your string session here
const client = new TelegramClient(session, apiId, apiHash, {});

(async function run() {
  await client.connect(); // This assumes you have already authenticated with .start()

  const result: Api.auth.SentCode = await client.invoke(
    new Api.account.SendChangePhoneCode({
      phoneNumber: "some string here",
      settings: new Api.CodeSettings({
        allowFlashcall: true,
        currentNumber: true,
        allowAppHash: true,
        allowMissedCall: true,
        logoutTokens: [Buffer.from("arbitrary data here")],
      }),
    })
  );
  console.log(result); // prints the result
})();