IBM 3872 User Manual page 55

Calling (Sending) Station
DTE
Modem/ACO
Ready - - - - - - - - -
- - - - - - - Not ready - - - - - -
' T
Request call------'-Go "off hook",
become busy and
not ready
DAA
t
Not 1eady
l
t
~Request
dial digit ..__Dial tone
Respond with dial
Line
digit
- - - - - - - - P u l s e dial digit - - - - - - - - - - - - - _ . .
t
Remove digit .. ~-----
1
Respond with next ,.
digit
I
(send all digits
in this manner)
Remove digit ...
~----
Drop digit 1equest
Pulse last dial
digit
t
Drop digit request ••
~Request next d1g1t
Answe1 ing (Receiving) Station
DAA
Modem
Not ready _ _ _ _ _ ,._ Not ready - - - - - - R e a d y
Stop ringing,
become ready
I
T
- - - - - · G o "off hook",
become ready
+
!
~
Signal connection,
-4----------._-14------------
Generate answer
become ready tone
Drop ca 11 request,
raise request to
send Become not busy,
Drop digit request,
-----remain "off hook",
generate equalization
signals
--~--------....if-I----------_.,
Equalize,
DTE
+
synchr;nize
Delay/clamp, equalize, synchronize
-'--------.....ii--,._----------
Generate equalization signals
t
~
Clear to send
t
Send data -------Modulate carrier
~
.
Drop send
request~
Finish sending
----1------------i--------------
Demodulate
carrier
t
Received data
----~
t
~Drop
clear to send,
stop carrier
r-
Become not ready ~ Go "on hook"
~
Become not ready ..____Become not ready,
disconnect
Become ready again
Figure 3-12. Automatic Call, Automatic Answer (Switched Network)
Sense end of data
t
i
~Go
"on hook"
4----
Become not ready
Become not ready,
~
Become not ready
disconnect
-i
Become ready again
Special Feature Descriptions 3-21