Because it's less than $2500, you can list it as a communications expense. Under Business Expenses, select Other Common Business Expenses. Scroll down and elect to start/update Communication. You can enter it there.

In the past, this would have been considered an asset that was depreciated over time. But due to changes in tax law you can just expense the phone under the safe harbor di-minimus act. More tax advantageous that way, to claim/deduct the expense all at once in one year.