Any ideas how I can find out when the Nokia 5100/6100 phone series started? When were these product lines introduced? Is there a single source that would have this kind of information for various phone lines for different manufacturers?
That would be interesting--a museum website dedicated to the oldie but goldie gooden cell phones of years gone by. Nokia still lists on its website many of the phones it released in years past. As far as release dates, that would be extremely hard to track. Each continent and each market and each carrier had different release dates. Even now, you can find TDMA phones available from SunCom that ATT has yet to market (if at all).
I would start my search by sending a brief inquiry to the Nokia public relations department. Can't hurt, and they might well take your request to heart and send you more than you ever wanted to know. Otherwise, I'd roam the archives of the telecom and cellular newsgroups. Try Google! I'd also try the archives of the major wireless publications (Wireless Week! for starters -- www.wirelessweek.com)..