Specifications

AN93
Rev. 0.9 201
As shown in Figure 68, the V29FastPOS protocol looks different than the older, slower, V.22-like protocols. It is
also half-duplex, and each participating modem uses the entire spectral space available in the telephone line.
A receiving modem recognizes that the calling modem is V29-capable by detecting the V29 Calling tone at 980 Hz.
Another example with some more SDLC oriented data is provided later in this document.
Figure 68. Appearance of V29FastPOS Protocol
DTMF dialing.
V29 Calling
Tone (980 Hz).
Answer Tone
(2225 or 2100 Hz).
Answering modem
sends training pat-
terns and packet(s).
Calling modem sends
training patterns and
packet(s).
Modem exchange packets.