As a strictly legal matter, you would prepare a return in TurboTax using your father’s information. The address on the tax return is where he would want mail sent, it does not have to be his prison address if he is OK with getting mail at your house. Print the tax return and take it to him in prison to sign in ink and then file by mail. Or, you can mail him an IRS form 2848 power of attorney form that will delegate to you the ability to file a return for him. Then you would print the tax return and sign it and mail it to the IRS with form 2848. I suppose the difference would be that you can mail him a form 2848 and have him sign it and mail it back to you if you do not live close enough to the prison to take a completed tax return to him. If he does not have a current bank account, the IRS will mail a check—that could be mailed to his prison address if he has a way to cash it, or it could be mailed to your address.
https://www.irs.gov/pub/irs-pdf/f2848.pdf
As a practical matter, if you prepare to return in his name and e-filed it as if you were him without using form 2848, the IRS would probably never bother with it as long as no one complained. You would still use the address where you want the IRS to send mail including a check, which he does not have to be his prison address. The IRS does not use the phone number, that might be used by TurboTax or your state but if he has no income and is only filing to get the federal stimulus, you don’t need to file a state return. It would be OK to use your phone number in either case.
I would probably go to signature route or form 2848 just so everything is legal and proper.
