Something to be considered in a DISPLAN is the destruction of the landbased telecom’s network. Celluar phones rely on the cell stations, the cells rely on power and at least to some extent the wired telecom network.
Calls by military and emergency workers caused satellite phone traffic to spike to 3,000 percent of usual levels after Katrina … To get more airwave frequency to accommodate that volume, Iridium had to get approval from the FCC and other similar agencies around the world.
- Greg Ewert, Iridium Satellite LLC. 
Crisis Communications Network Criticized
September 23, 2005 [Washington Post]
Federal Communications Commission (FCC) Chairman Kevin J. Martin has called for a mobile and wireless communications system to allow first responders to coordinate in an emergency, blaming mismanagement of the Hurricane Katrina response on the lack of such a system. The next generation of emergency response should use satellites, since disasters can destroy the ground-based communications infrastructure. Satellite phone traffic jumped 3,000% during the Katrina response, requiring satellite companies to obtain emergency frequency allocations from various countries. Many lawmakers in Congress are calling for radio spectrum currently used for television to be transfered to first responders; the transfer was authorized around 1995, but television broadcasts have not yet released it. Martin has called for “smart radios” that can work on multiple emergency networks as needed. Many local agencies invest in their own communications systems and are unwilling to cede control to other agencies. 
Hurricane Katrina has revived calls in Congress to set a date for police, fire departments and emergency medical services to take over radio frequencies set aside for them nearly a decade ago but still used by television broadcasters. The 9/11 Commission Report, which documented in painful detail the inability of police and firefighters to communicate with one another as they tried to save people in the World Trade Center, cited freeing those frequencies as one of its key recommendations.