Nokia 3120 (the original small silver S40(?) phone with the colour display, not the later 3120 classic) was the employer-issued phone I used a lot when I had to do deals/negotiations. Twas on an Orange business contract I recollect. Plenty of money/business went through that phone. Never managed to get hold of a data cable alas for calendar sync.
Still works fine, has a t-mobile vintage payg sim in it and is used for emergencies at home.
31 day battery life sounds interesting so may look at the retro offering.
Coat: mine's the one with that very small phone pocked sown into the lining...