AT&T and T-Mobile USA have reached a temporary agreement to enable roaming on their networks to customers of both providers in areas most affected by Sandy. Customers will be able to place calls as they normally do, but the calls will be carried over whichever network is up and running in their area, CNET reports. The companies say there will be no roaming charges or fees associated with the calls and subscribers’ current service agreements will remain in place. The arrangement is possible because both carriers run on GSM and UMTS networks. Yesterday the FCC said that 25 percent of cell sites in Sandy’s path had been knocked offline. The FCC said today the number had improved by a few percentage points but couldn’t provide an exact number, according to PC Magazine.

Separately, Verizon worked to repair damage at its Lower Manhattan headquarters where 3 1/2 of 5 basement floors were still flooded. Switching equipment on upper floors wasn’t damaged but connections for incoming lines remain under water. Verizon was also working to restore telephone hubs in other locations downtown. The company announced this afternoon that workers had successfully erected a temporary wireless antenna in Jersey Ci]oty across the Hudson River from Lower Manhattan.