Point to point leased lines can take advantage of the backup interface command. Use two dialer profiles (one for each branch) rather than dialer maps to allow both sites to be backed up.
Note if you are using VPNs or there are other routers between your central site and branch offices, you will need to take a different approach (one that can detect loss of the end-to-end connectivity even though the link to the ISP is still up. See the Redundant VPN white paper on my web site for some ideas.
Good luck and have fun!
Vincent C Jones
www.networkingunlimited.com
