If the job is in progress(meaning 'start job' or 'on my way' has been hit and 'finish job' has not), the employee on the job will receive the message in their app. If the job is NOT in progress, the message will go to the Dispatch/Messaging POC (point of contact).
You can set who your POC is by following the steps here. If no one is selected, it is the first Admin who was added to the account.
Keep in mind, the text response will only come through as a message on the app, not on the web portal.