If the package that you have bought has WhatsApp and SMS message sending feature in it, you can send WhatsApp and SMS messages to your customers with StockMount. If your package does not have that feature, you can buy these features in-app purchases.
If your customers phone number that was entered in contact information is a cell phone number, you can use these features. If your customer uses WhatsApp, StockMount confirms it and enables you to sent WhatsApp message. If your customer does not use WhatsApp, you can only send SMS message. If your customer did not enter his or her mobile phone number on contact information section and you found his or her cell phone number somehow, you can save this number to the system. This number is remembered by system on your customer’s next shoppings. Thus, you can send WhatsApp or SMS message to your customer whenever you want.