You can use SMS replies to enrol contacts in secondary workflows, or trigger actions within the same workflow.
To trigger a decision from an SMS reply, you first need to send an SMS. Read this article for more information on how to add SMS messages to your workflows
Triggering an "If/Then" condition with SMS
Once you have created the action to send an SMS, add another action choosing the "If/then branch" option from the slide-out action menu:
From the filter list, choose "MessageMedia: SMS Received":
Next, select the condition of the message that you want to trigger the next action:
For each option, you will need to enter the specifics in a subsequent step. For example, if you wish the action to be triggered by the content of the inbound message then you will need to specify whether the condition is inclusive or exclusive of specific words or strings, or if the message starts or ends with specific words or strings:
Once you have saved your conditions, you can then add an action for each outcome: