How to send multiple sms through an android application

In my application I'm trying to send multiple SMSs, but sometimes it does not send.

smsManager.sendMultipartTextMessage (telefones.get(i), null,smsManager.divideMessage("Mensagem"), null, null);

try {
    SmsManager smsManager = SmsManager.getDefault();
    for (int i = 0; i < telefones.size(); i++) {
        smsManager.sendMultipartTextMessage(telefones.get(i), null, "foo"), null, null);
    }
} catch (Exception e) {
    e.printStackTrace();
}

I have an Arraylist with the phones, then I try to send sms to all of the vector with a for and using smsManager, but sometimes it does not send, does anyone know if it is a problem of this class?