Your company can let you message customers from the driver app. If you don't see Customer messages in your menu, it's turned off for your company. Your office decides that in Settings → Customer Experience → Driver messaging.
Where messages show up
Depending on your company's setting you see one of these:
When the office shares a conversation with you, you get a push notification and it shows up in Customer messages. If a conversation you could open before disappears, the office may have stopped sharing it, or the customer is no longer on your route.
Replying
Open a conversation and type in the box at the bottom. The line under the box tells you where your reply goes, for example *Replies go out as a text to (815) 555-0102*. Replies always go out the same way the customer wrote in: text, email or portal. Texts go out from your company's business number, never your own phone.
Tap the phone icon at the top to call the customer instead.
Opening a conversation marks it read for you only. The office still sees it as unread until someone there opens it.
Messaging a customer about a job
Saw something on site? Open the job, scroll to Customer messages, write it, and send. The customer gets it by email and in their customer portal, and their reply comes back to the same place. You get a push notification when they answer.
On a shared truck tablet
The conversations shown are the ones for the driver who signed on with their PIN, not the truck.
What you won't see
Internal notes the office writes to each other, and messages from numbers or addresses that aren't matched to a customer, stay in the office.