It is important to take note of the possibility of 4G. A T1 circuit is 1½ Mbit/s. The minimum 4G standard of 100 Mbit/s is 66 times larger. Take a look at the graphic posted on my blog at http://keith.robertory.com/?p=560 for a better understanding of this. A cell phone running true 4G will have more bandwidth then an entire site serviced by a T1. We are right on the verge of a major cellular service shift. When setting up a site during a disaster, it is common to use one cellular data card (aka aircard) per computer. With these faster speeds, we can use one cellular data card to be the head of the site’s network.
My team has already successfully setup a network in a disaster with one 4G aircard providing connectivity for 30 computers. Granted it was rare that there were users on all 30 computers simultaneously surfing the net and streaming large files. But, that’s the point during disasters — and really even day to day. It isn’t about providing maximum bandwidth to each user all the time. Instead, focus on load balancing to provide enough bandwidth to meet the combined average need ~90% of the time. It is ok for the system to be a little slower during peak demand times. Set the user’s expectations correctly, and your team will get through it.
A cellular connection could be used to back up a wireline circuit. Advanced routers can handle multiple uplink connections with prioritization and failover settings. This will provide redundancy. It is better than two wireline circuits backing each other up when the backhoe cuts through the utility lines outside the building. Redundancy is nice. Diverse redundancy is better.
Your users in a disaster response will be on the computer only part of the time, with the rest of their time filled with other activities. If a disaster responder travels to a location and spends the entire time behind a computer, then the question should be asked: could that person just stay in the office or at home to complete the same work?
If this interests you, take a look at this post.