Create a account in https://numverify.com/ and verify the number is valid phone number or landline or which country it belong etc.

func validatePhoneNumber(number string) string{
  safePhone := url.QueryEscape(number)
    url := fmt.Sprintf("http://apilayer.net/api/validate?access_key="your key here"&number=%s", safePhone)
    req, err := http.NewRequest("GET", url, nil)
    if err != nil {
        log.Fatal("NewRequest: ", err)
        return "error"
    }
    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        log.Fatal("Do: ", err)
        return "error"
    }
    defer resp.Body.Close()
    var record Numverify
    if err := json.NewDecoder(resp.Body).Decode(&record); err != nil {
        log.Println(err)
  }
  fmt.Println(record)
  if (!record.Valid && record.LineType !="mobile"){
    return " not a valid mobile number"
  }
  return "valid number"
}

It return the string, if the given mobile number is valid.