Rent a number when the same app may send another code before you are done with that line. NonVoIPService lists US long-term rows for 1, 3, 7, 14, and 30 days when the provider has stock. A missing duration is not available.
You still read messages in the dashboard or API. You do not receive a handset, a voice plan, or a number you can port. When the window ends, new texts require a new order. The rental page states that plainly, and pricing is where the current sell price appears.
There is no claim here that a rental is cheaper than a phone plan. Compare the live price with the job you actually have. Search interest in “rent US number” is an estimate, not proof that the 30-day row is in stock.