How could I set up redundant HSDPA (3G) modems for my internet connection?

Question

How would I go about setting up four 3G (I'll use this as a shorthand for GPRS/EDGE/HSPA etc.) modems, each one for a different network, on my machine so that if my first choice network gives bad throughput or goes down, my internet connection will move to my second choice, until I give up and look for a coffee shop with wifi?

Ideally I'd like to eventually package this set up up into a wireless access point outside of the machine, so 'bonus points' for telling me where to ask about such a more technical development of this concept.

Answer 1

Rather than worry about the fact they are Wireless, you just need to research redundant network failover. Examples of the many solutions and articles available.

The basic answer: you need a router, whether manually configured or bought as a one-stop-solution, that can route traffic out over two or more completely disparate networks. There are linux distros that can do this (so for a large time investment you can save money), as well as pre-built solutions. Most pre-builts only support two connections though, so for supporting four you may need to go the custom route.