5.8.2.1. Real Dial Tone (Time-Dependent) From the Central Office (CO) 
If the remote central office also actually applies a dial tone, you
must set the following parameters for the outgoing seized trunk to apply
the real dial tone to the outgoing user from the central office.
- COP parameter: TDED (line with time-dependent central office dial tone)
- AMO TACSU:DIALVAR=x-8 (where x usually has the value 0)
- AMO ZAND: TYPE=ALLDATA, CODTN=NO
- You must configure the outgoing seized circuit for the proceed-to-send signal (COP
parameter:
SDL).
The sound path of the outgoing user is switched to the circuit when the dial tone from the remote central office has been detected.If only the parameter TDED is set but not the corresponding type of dialing, the OpenScape 4000 generates the CO dial tone itself and then applies it when this tone is detected on the line (time-dependent).