V.92¶

V.92 is the last of the dial-up modem standards (2000). It keeps V.90's 56000 bit/s download and adds three things:

• Quick connect. A shorter start-up: the analogue modem can skip parts of V.8 and the line probing, so the call connects sooner.
• Modem-on-hold. When call waiting rings during a modem call, the modem can put the data call on hold while you answer the phone, then carry on.
• PCM upstream. The upload direction can also use the digital method, raising it from 33600 to up to 48000 bit/s.

This page is about D-Modem as the digital end of a V.92 call (the internet provider's side). For the analogue end, see V.90 and V.92: the analogue modem. For every signal and setting, see the technical details.

What D-Modem does¶

As the digital modem, with AT+MS=92 (the default) on a digital line, D-Modem supports all three features:

• It answers a calling modem's quick connect request and skips the long start-up.
• It holds the call when the analogue modem asks, for as long as the modem asks, and picks it up again after.
• It receives PCM upstream, and can change the upload speed during the call as the line changes.

In the tests the Conexant HSF modem reaches 52000 bit/s down and 41333 up with PCM upstream, and the ESS modem 49333 down and 41333 up (see Interop).

Settings¶

• DSP_V92=0 turns V.92 off (the call is V.90 instead).
• DSP_V92_QC=0 turns quick connect off.
• DSP_V92_PCMUP=0 turns PCM upstream off.