There is nothing built into Store that allows it to take cash orders but you could easily create an admin page with Store templates for your employee's then use the Manual gateway which is perfect for cash, checks or similar orders.
With phone orders you could do the same thing or if customers are giving their card number over the phone you could use whatever gateway you are normally using on your site. The only thing is if you are creating orders they would not be linked to a customer's member account if you were logged in so you would probably be best to to use some other form of authentication to block the page from normal users being able to see it and whoever is taking the phone order to be logged out. I would also recommend that you have the person taking the phone get the persons email address so that if the user creates an account existing orders will be linked to their account automatically.