You can use IRB and GRE tunnels. I had to do this for a company that we acquired that was using their routers to bridge traffic over frame-relay. To give them a migration path I configured layer 3 subnets across the frame-links and used GRE tunnels...
What are your IOS versions? We had something similar happen when we had 12.4... connecting to 12.3... Do you have the same keepalive configured on both sides? Do you have the problem if you take the keepalive off of your GRE tunnel interfaces? I ...
You can do this by creating two subnets (VLANs) on the 800 router. Create a nat statement that NATs the subnet you want to give Internet access. Create a crypto map that only tunnels and encrypts the other subnet that requires access back to corpor...
There is also a DB25 to DB9 connector that comes with the 1841 routers with a part number of 29-4043-01 stamped on it that works nicely with the standard Cisco DB9-RJ45 console cable for connecting to a modem.
Not sure what your budget is, but you could use an 1800 series router with a WIC-1AM. You should check to see if you could get DSL at some of these sites. It is reasonably priced and would open up more options for your gear. Another lower cost opt...
