Don't allow SMS to be sent out if no phone numbers are checked off

Question

When sending out SMSs, the system does not allow me to proceed if I don't write anything in the email field, or if I don't choose a time to send it out. However, if I don't check off any phone numbers, then it does not prompt me. Instead, it allows the text to go through and a message pops up that the price was $0. Then I have to set up the entire text again (which can take time if using mail merge fields. Can you change this, so that the system does not allow a text to be sent if no phone numbers are checked off? 

Answer 1

This is already after its setup. Added a message when sending zero so you can press NO.

Comments

Thank you! I appreciate how quickly this was done!