Problem about disconnection

we have Installed an Asterisk 1.4.24 system together with a Sangoma card which has got 8 ports FXO on a PC. All those & ports have been connected to the TEM 824 Panasonic PBX.
However we faced with a problem which is one line some times does not get disconnected and also two lines sometimes get bridged together with no reason. It should be noted that no Panasonic extension is busy in this situation. We have set busydetect=yes & busycount=3 on the chan_dahdi.conf and also after calculating frequency and cadence of the lines and Panasonic extensions, we found out that the frequency for Panasonic lines should be equal to Freq=390 and cadence=500/500. Frequency for the pstn lines should be equal to Freq=430 and cadence=500/500.
Care should be taken as there is no separate lines between panasonic Ext and PSTN lines , we have to use the same FXO channels for connecting to both panasonic Ext and PSTN lines.
At the moment we are using dahdi driver for Sangoma card so we are looking for a
file such as zonedata which used to be in zaptel driver in order to change the busy tone Frequency an so on.
We were wondering if anybody could advise us regarding this issue at your earliest convenience time.