You are able to call or SMS a Customer from within their Customer profile if you're on a phone. This function is not supported on tablets.
To send an SMS to one Customer, locate your Customer in the Customer List
Tap on the Customers' name
Scroll down to the Contacts section and tap directly on the Mobile / Cell field
Tap Call to call your Customer
Tap SMS to send an SMS to your Customer
When you send an SMS in the Android app on an Android mobile phone, that SMS is sent from the phone's mobile plan. When it's received by the recipient the 'from' number is the mobile number of the phone it was sent from. As this SMS is not sent via Ovatu it is not noted in the Marketing > Sent SMSs page in the web browser version of Ovatu and does not cost SMS credits.
When you send an SMS in the Android app on an Android tablet that SMS is sent from one of the online messaging apps on the tablet, such as Google Hangouts or Facebook Messenger. You should see the a pop up showing the installed apps on your table for you to choose from. When it's received by the recipient it's received 'from' the Google account used on that tablet. As this SMS is not sent via Ovatu it is not noted in the Marketing > Sent SMSs page in the web browser version of Ovatu and does not cost SMS credits. Otherwise you can open the web browser version of Ovatu on the tablet and send an actual SMS via Ovatu. This is done in the Ovatu app by tapping on Menu > Open web app.