Hi Samir,Basically your case is related to dial in ras case. You have to confgure your modem properly. As it seems that your modem is not properly bind with the router. Your modem profile setting is not properly matched to receive the callyou can try...
You can try out by putting blind routes like ip route 0.0.0.0 0.0.0.0 ( remote wan ip address of int s0> and ip route 0.0.0.0 0.0.0.0 ( remote wan ip address of int s0>the AD and metric value for both the routes are same so loadbancing star...
You can configure the dialer interface and make your dialer interface as the backup interface.In this way all the interface vcan use the same physical port for dial backup and for chap configure for authentication as ppp authentication chapand for fr...