It's not about your phone. It's about 147 phones.

Electronic devices in general are put away to keep the aisle clear and prevent FA's from having to check if something is in "Airplane Mode" (Just having them completely off is easier to manage and administer) while the A/C is in a critical phase of flight. There are both FAA and FCC prohibitions on cell phones because they OBVIOUSLY DO interfere with radio communications, including radio-based navaids. The FCC prohibition is more related to overloaded networks. Talk to an engineer. Or set your phone next to a radio.

20 minutes with all your crap put away isn't much to ask.