Notifications are automatically sent to staff members logged into ServiceM8 on their iPhone/iPad, when:
A job is scheduled to them (or a scheduled job booking is changed) sometime before midnight that day.
A job is allocated to them (e.g. as 'Urgent', or in a certain booking window such as 'During Business Hours'.
A instant message is sent to them through ServiceM8 (messages can be sent to other team members through the Activity tab of the app, or through the staff member icons in the Dispatch Board online).
If staff aren't receiving notifications, it's usually due to Push Notifications not being enabled on the device, or enabled for the ServiceM8 app.
To double-check ServiceM8 notifications are enabled on an iOS device:
Go to Settings > ServiceM8 > Notifications, and enable the Notifications options: