my computer is in a LAN, and I am connected to the Internet via gateway 192.168.0.1
and DNS 213.5.138.34
but sometimes (often) I'm loosing my connection because of ISP
then I need to connect via dial-up modem
I'm using chat
these are my scripts:

'' ATZ
OK ATDP0134200
CONNECT ''
ogin: impuls
assword: infotel

this one is called dial-btk
and
ppp-on

pppd connect "chat -f dial-btk" /dev/modem 38400 \
lock -detach crtscts modem noipdefault defaultroute noauth \
ipcp-accept-local ipcp-accept-remote

then I establish the connection but result is:

Serial connection established.
Using interface ppp0
Connect: ppp0 <--> /dev/modem
not replacing existing default route to eth0 [192.168.0.1]
local IP address 212.39.77.55
remote IP address 212.39.77.242

so I have to disable my eth0 before start dialig
ifconfig eth0 down
Why DEFAULTROUTE doesn't act as it should
I tryed and this program pppsetup, but the result is the same
distribution is Slack 9.1
Have you any ideas?