I always thought a recovery image that could send and receive calls and sms would be awesome. No internet, not even 2g. Just phone and sms. Maybe some contacts (name / number tuple) that'd exist separate from the main systems contacts.

Having had my "Phone" crash due to software glitches, leaving me unable to dial 911, I 100% agree this would be a great boot-time switch.

I have this on my Android phone, it's called "Ultra STAMINA mode". Only GSM calls are allowed, no WLan, no data, selected apps only and a limited user interface. Did somebody measure the lifetime it adds to a phone with 5% battery left ?