Users can set it so jobs can not be book unless the have an Email and/or a Phone Number

Green: We can find this setting in the Corporate Identity found in Manage > Admin > Settings > Corporate > Identity
Red: This can actually vary from branch to branch so we can click on the little pencil next to the branch you want to edit.

Purple: is where you can turn on or off for a Phone Number is required for booking a job
Orange: is where you can turn on or off for a Email Address is required for booking a job

This is what it will look like if you have this feature enabled and the sales rep tries to book a job without the field required filled out