What carriers can keep their service running 7 days in a row

Can anyone tell me of a carrier (from your personal experiences) that keeps all phones online and reachable for a full week? This means, that during the week a) all calls progress with a decent MOS, or good speech quality; b) all calls made to outside working phone numbers are completed (ringing, busy, etc.) with correct call-progress tones; c) the carrier doesn't 'adjust' the network such that you need to reboot your phones. Thanks, Oh, and please, Carriers, don't respond, except as a rebuttal to anyone suggesting that your service does not meet the '7 day criterion'