package main

import (
  "fmt"
  "strings"
  "net/http"
  "io/ioutil"
)

func main() {

  url := "https://api.sms.to/sms/send"
  method := "POST"

  payload := strings.NewReader(`{`+"
"+`
    "message": "This is test and \n this is a new line",`+"
"+`
    "to": "+35799999999999",`+"
"+`
    "bypass_optout": true,`+"
"+`
    "sender_id": "SMSto",`+"
"+`
    "callback_url": "https://example.com/callback/handler"`+"
"+`
}`)

  client := &http.Client {
  }
  req, err := http.NewRequest(method, url, payload)

  if err != nil {
    fmt.Println(err)
    return
  }
  req.Header.Add("Authorization", "Bearer <api_key>")
  req.Header.Add("Content-Type", "application/json")

  res, err := client.Do(req)
  if err != nil {
    fmt.Println(err)
    return
  }
  defer res.Body.Close()

  body, err := ioutil.ReadAll(res.Body)
  if err != nil {
    fmt.Println(err)
    return
  }
  fmt.Println(string(body))
}