Occasionally I want to use a feature, and assume it must be there, then I am disappointed to find it's not. 

This was such a case. 

It seemed, within the SD-Mobile interface, I ought to be able to double-click on a customer's telephone number, and thereby auto-initiate sending of a text message to that number. 

By "auto-initiate," what I mean is the system should open the SD-Mail interface with that telephone number inserted, and ready-to-go as a send-to SMS target. 

Hmmm. 

Turns out that feature did not exist. 

Now it does. 

Just double-click on a customer's telephone number as present in the JobDetails page, and you'll see. 

(Of course, you'll have to type your message then click to send before anything actually goes out.)