Tri-band phone with >5 day battery life between charges..... No camera, FM radio, GPS, MP3, camera, WiFi, Internet connection (except GPRS if you must), 'apps' (whatever the hell they are) or other largely pointless trivia - just voice and text. Clicks into the car's hands-free and speakers too.
All you really need from a phone, unless you're a geek or a pre-teenage girl!
Nokia 6310i - still the best there is!!