By employing pulse code modulation (PCM) in the upstream direction, V.92 supplies a data rate of up to 48kbps — a significant improvement over V.90 which uses quadrature amplitude modulation (QAM), the same upstream modulation as V.34, for a maximum speed of 33.6kbps. This increase is made possible because the V.92 clock is set by the demodulation process and used in the upstream modulation. This will prove most useful in applications that involve large data transfers from user to ISP: VoIP, for example. The V.92 Server Modem is a digital modem with a maximum bit rate of 56kbps transmit and 48kbps receive. The V.92 Client Modem is an analog modem with a maximum bit rate of 56kbps receive and 48kbps transmit.
V.92's downstream rate remains unchanged from V.90 at 56kbps; however, this modem does offer other benefits over V.90. Modem connection time is reduced through faster handshaking. The shortened start-up time is accomplished by buffering information on past connections then, when a match is found, handshaking can immediately begin at a previously negotiated rate. Connection time for V.92 is up to 50% quicker than V.90 for buffered connections. When online, users have the ability to put the 'Modem On Hold' (MOH) and can receive a phone call without having to disconnect from their Internet session. There will, however, be a time limit of between 0 to 16 minutes, which is set entirely at the discretion of the ISP.http://www.gaoresearch.com/products/modemsoftware/other/v92.php