Currently, I design a ISDN WAN, which at both end router able to trigger ISDN call whenever the lease line is down. Let say, site A and site B. Lease line is connected in between. Whenever the lease line down, ISDN at site A must call to site B, BUT if the ISDN site A fail to dial, ISDN site B will definitely trigger the ISDN call to site A. I just wonder how to do this. Can anybody advise?? thank you.