Whilst studying for the CCNA I have come up with some scenarios with ISDN that I cannot answer, I suspect they are beyond the scope of CCNA but I am still interested in knowing the answer.
Q1 - If I have three sites A, B and C. Each site has an ISDN-2 connection. Can Site A call sites B and C simultaniously, using one B channel for each link? If so can it work inverse with sites B and C initiating the calls to site A?
Q2 - Sites A and B normally communicate via a leased line but have an ISND-2 each counfigured for DDR. There is continuous traffic in both directions on the link. If the link fails A tried to call B and B tries to call A due to "interesting traffic". What happens, are the lines engaged, do the calls complete which site gets the bill for the call?