REAL AUDIO MODEM HANDSHAKES (Version 5 & up):
To hear good & bad modem handshakes (x2 & Flex) - Click here
To hear 3Com V.90 handshakes - Click here.
V.90 null speedshift & retrains-Click here
3Com V.90 client to Livingston V.90 server handshakes - Click here
Lucent V.90 client to 3Com V.90 server handshake - Click here
Lucent V.90 version 5.15 with new DIL tones - Click here
Rockwell V.90 client to Ascend V.90 server with new DIL - Click here. (Thanks
           to Jim Bell for this handshake.)
3Com Courier & Sportster 5.0.0 V90 handshakes - Click here 
Lucent V.92 version 8.02 to V.90 servers - Click here
Lucent V.92 version 8.02 to V.92 test server - Click here

Conexant Soft56 V.90 in mp3 format (Requires mp3-compatible player)
From Andy in Australia 

Note on V.90/V.92 Handshakes: Near the end of a V.90 handshake, a new process was added: DIL (Digital impairment learning). The (often distinctive) sound at this point is determined by the client modem - not the server. It also depends upon the firmware version in your modem. There are other (more subtle) variations in the handshake that depend upon the type of server modem and firmware you are connecting to.

V.92 Handshakes

Quick-connect can significantly reduce handshake time using one or more 'shortcuts'. The actual handshake time with quick-connect enabled may be almost the same as a V.90 handshake (first example), to almost 50% shorter (second example):

USR V.92 Quick Connect #1  (.mp3 format)
USR V.92 Quick Connect #2  (.mp3 format)
Credit: Recorded by David Hollman with a USR5686E 

Creative V.92 ModemBlaster QuickConnect (.mp3 format)
Credit: Pim Heijnen from the Netherlands using Conexant chipset Creative Model #DE5721

V.92 Modem-on-hold and PCM Upstream connections - are available on this page courtesy of Jarek Niewczas.