|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|
|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|
|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|
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