Hi I am from Bangladesh.The number of e-mails used in our country is very limited But the number of mobile users is much higher.They do not understand the email But they understand the SMS. That is why emailing or sending sales receipts is not going to work ! In that case, sending SMS is very helpful for us. 

How to send the invoice or sealsreceipt via SMS to the customer ?

If this option is not in QuickBooks, please add it.