DAHDI busy pattern prob

Hi guys :
iam so confused about this configuration ,and i really need your help please.
i need to setup dahdi to detect busy tone from the first ringtone and make hangup immediately,
i did this config to dahdi:
busycount=2 (or 1)

when i specify busycount to 8 or 10 or …, it count busy tones exactly as its specified and do hangup ,but when i set to 1 or 2 or 3 it doesnt read it and do 4 busy tones to do hangup ,as if its been setted as default to be 4 , i dont know ,do you know where i can change it .