asterisk users - Nov 2003 - surpress dial tone on TDM400p

i've already tried to change the indications.conf to the following:

dial = 0/1500

but the dial tone still persists

i am using the following workaround but obviously not a clean
b'cos it just replace dial tone with some other tone.

in zapata.conf
    context=spec
    immediate=yes
    signalling=fxo_ks
    channel=>2 ; TDM400p-1

in extensions.conf
    [spec]
        exten => s,1,Background(pbx-silence)

        exten => _XXXX,1,Dial(Zap/1/${EXTEN})


please help,
patrick