The phone a parent will actually carry is the one he can use without asking for help, and that is rarely the phone with the longest feature list. Compare phones on the criteria that decide whether they stay in his hand, not on box claims.
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Test it in his hand
Put the candidate in his hand, ask him to answer a call without you touching the screen, then ask him to call you back. Note whether he can do it without looking, whether the buttons sit where his thumb expects them, and whether he can hear the ringer in the room where he spends most of the day. A phone that works only at your desk is not the phone for him.
The criteria that decide it
Compare the ringer and speaker volume, the size and spacing of the buttons, and whether one press reaches a stored contact. Check whether he can reach emergency calling without unlocking the screen. Ask the seller what any emergency or fall feature needs to work, such as a paired device, a subscription, or a charging habit, and ask them to show you where the feature sits in the menu.
Check where he will keep it. A phone in a pocket, on a lanyard, or on a bedside charger each asks something different of him. A phone that is charged in one place and carried in another is a phone that is missing when he needs it.
Check the passcode and the screen lock. A passcode he cannot remember will end up written on the back of the phone, where anyone can read it.
Check the account. Who holds it, who receives the bill, and whether the plan lets you change the minutes or data without a penalty. Ask whether a missed call can send a notice to your own phone, if the plan supports it.
Check the coverage in the rooms he uses. A signal in the kitchen is not a signal in the back bedroom, and you cannot judge that from a store display.
What not to trust
Do not decide on a box claim or a review you cannot check against his house. A feature that sounds like safety is only as good as what it does in his hand and in his home.
The next move
Pick two phones on the criteria above, set the speed dial and emergency contact on the one you choose before you hand it over, then run the in-hand test in his kitchen and bedroom with him watching. The Start Here page has the order to run the whole process in.