Here's is some data Art Bell should know about..
Completely disabling the GPS signal would also disable the majority of Digital Telecommunications within approximately 24 hours.
All digital telecommunications today require a "timing reference source" to keep terrestrial and "over the air" things in sync. Before GPS, extremely high tolerance clocks were used. With the advent of GPS, timing is largely derived via the matrix of signals emitted by GPS satellites, which is a much cheaper source (free) than expensive stratum clocks.
A shutdown of the GPS signal would not immediately disable the network as a hierarchy of the clocks remain and are still installed in telecom equipment. The most important components such as the largest telephone switching computers highest in the hierarchy of the telephone network will remain on-line indefinately however equipment at the edge such as Cellular Telephone base sites could be off-line in an hour or less. Especially those that use the CDMA air interface standard (Verizon, Sprint PCS). Network connections to smaller telephone switching computers would start to fail in 24-48hrs.
I don't know about immediately, but as soon as the inevitable timing hits started, you're absolutely correct, it would deteriorate rapidly. A surprisingly large amount of DoD traffic goes over the Telco lines.