Bookem supports two way communication - between you and your clients - and every message (email and SMS) is tracked and logged for your records.
In order to see what messages have been sent, including SMS reminders and replies from clients, invoices, and online form links, go to "Clients - Messages" and pick sent or received from the top line.
NB. This is another reason you need to make sure each team member has their own login, as the messages are tracked against a user login.