From HwB



25 PIN D-SUB MALE at the DTE (Computer).


25 PIN D-SUB FEMALE at the DCE (Modem).


Pin Function Description Circuit EIA
1 unused
2 Digit Present A signal given to the ACE indicating that the digit lines contain a digit DPR
3 Abandon Call and Retry An indicator signal from the ACE that it could not make a connection. Could be 'busy'. ACR
4 Call Request A signal from the DTE that tells the ACE to go 'off hook' CRQ
5 Present Next Digit A signal from the ACE to the DTE to indicate that the ACE is ready to receive the next digit. PND
6 unused
7 unused
8 unused
9 unused
10 unused
11 unused
12 unused
13 Distant Station Connected Indicator from ACE to DTE that the call is succesfully made. DSC
14-17 Digit Signal Circuits Four lines containing a parallel BCD dial digit (10 digits, plus control digits) NB1-NB8
18 unused
19 unused
20 unused
21 unused
22 Data Line Occupied An indicator that is used by the ACE to let the DTE know that the line it wants to use is used by another device. DLO
23 unused
24 unused
25 unused