Scheduled SMS later in Workflow

Is there a way to schedule an SMS at a scheduled date like a follow up? I would like to set up a follow up SMS for a week later after a trigger event.

I am trying to build a workflow that will trigger after reaching a voicemail box of the recipient, if the recipient is not in my contacts list, like a new client. After being triggered it should send a follow up text then a week later send another text, for 3 weeks.