5.8.8.2. Operational Configuration 
The COP of the main station line must include the parameter DTN (dial
tone on incoming seizure). Determine the dial tone in the AMO COT. It
is also possible to have a synchronous announcement for the proceed to
select signal.
You must set the DIALTYPE in the AMO TACSU to DTM-x and you must set
the DIALVAR to 5-0 (line with old loop start loadware BWMSCH) or 4-0
(all other loop start signaling).