Before you set off
Tell the customer you are coming
Why this step
Open a job and use Message customer. You pick from a short list your office wrote — "On my way, about 20 minutes" — and the only thing you type is the number of minutes. It goes out in the customer's own language, and lands on the survey record so everybody can see what was promised.
Checkpoint
The message you sent appears in the job's history with your name against it.