5.3.6. Real Dialtone from Central-Office 
If the outgoing seized Trunk should hear "Real Dialtone"
from the connected CO and should connected to the Subscriber or the transit-trunk,
the following parameters are to set:
This function is only possible if the outgoing trunk has set the parameters
"waiting for dialtone" or "line with no start dial signal".
The COP-Parameter "TDED" must administrated to the existing
COP-Parameters.
The CO must send "Dial-Tone"
In AMO-TACSU the Parameter DIALVAR=X-8 is to set, "X" is
normally to set to "0"
The AMO-LODR is to administrate only with END (no ECHOFELD) so that
the dial-tone can be heard allready when dialing the access-code.
Also the AMO-LDPLN is only to administrate with the access-code.
Remark: The dial-tone from the CO must be released from the CO after
getting the first dialed digit.