Hello TigerTanaka, Thanks for being part of the Community. We understand wanting to activate an older phone for your dad.
Digital certificates identify computers, phones, apps, and other devices for security. Just like you'd use your driver's license to show that you can legally drive, a digital certificate identifies your device and confirms that it should be able to access something.
Due to the age of the phone you are trying to activate, it does not have the security necessary to connect to digital services.
We would recommend locating a more up-to-date phone.
