If you need to view previous messages sent to and received from a fieldworker, you can view the SMS history. You can do this by following the below steps:
Go to Fieldworkers
Click on a fieldworker, this will take you to their full profile
Click SMS Log
Select if you want to view outgoing or incoming messages
Alternatively,
Go to Fieldworkers
On the fieldworker, click Actions
Select SMSInbox this will show all messages sent and received by this fieldworker
To reply to an SMS message, click Reply below the message