iPhone 17 Pro Max has weak signal inside house

That's the way radio waves work. Some building materials and methods attenuate them more. Turn on WiFi calling if your carrier supports it.

jammie291 wrote:

weak signal on iphone 17 promax inside my house

That's pretty common. I live in a row house which means my house is attached to other houses on both sides. My cellular signal is very weak except in my second-floor bedroom at the front of the house. A week ago, we had a twelve-hour power outage, so I didn't have WiFi. I ended up turning the phone off completely to make sure that the battery didn't drain from the poor cell signal.

If you have WiFi in your house, that's what you should be using.

See also:

Make calls using Wi-Fi on iPhone - Apple Support