[Asterisk-Users] zapata.conf - callwaiting

[PHP Mechanic]

Hi,

I have callwaiting enabled by my telco, but my wife hates callwaiting so I 
tried to switch it off in * but it doesn't work:

zapata.conf
[channels]
busydetect=yes ; to test when a line is hung-up
busycount=6 ; to prevent suprious hangups
echotraining=800
echocancel=yes
immediate=no
usecallerid=yes
relaxdtmf=yes
callwaiting=no
callwaitingcallerid=no
threewaycalling=yes
transfer=yes
cancallforward=yes
callerid=asreceived

signalling=fxs_ls
group=1
context=PSTN
channel => 4

signalling=fxo_ls
mailbox=1
callerid="Real Phone" <1>
context=RealPhone
channel => 1

How do I switch off callwaiting in asterisk? What am I missing?