Here is a set of files from Sidekick 1/s era phones originally posted here:
Sidekick "new message" sound file
New Message.zip‎ (25.2 KB, 4606 views)
Attention.zip‎ (18.5 KB, 1244 views)
Blue Flute.zip‎ (36.1 KB, 802 views)
AIM.zip‎ (44.3 KB, 1127 views)
Bell Tree.zip‎ (58.0 KB, 556 views)
Bird Call.zip‎ (25.5 KB, 471 views)
Default Beep.zip‎ (24.5 KB, 639 views)
Ding-A-Ling.zip‎ (38.8 KB, 473 views)
Evil Overlord.zip‎ (33.6 KB, 485 views)
Frogs.zip‎ (25.1 KB, 427 views)
Future Ring.zip‎ (74.3 KB, 578 views)
Siren.zip‎ (43.7 KB, 497 views)
Wah-Wah.zip‎ (42.7 KB, 530 views)
I have also posted the files here on my SugarSync account (similar to DropBox):
https://www.sugarsync.com/share/bt8m248oxzcbv
hope it helps.