Toll-free and teleconference services on 9/11

How well did toll-free and teleconference services work in 9/11? Four ISPs told me they couldn't get through to their upstream's toll-free customer service numbers for most of the day on 9/11. And one ISP told me their teleconference service couldn't set up a call for unspecified reasons. There have also been several reports in the newspapers, and from customers that customer service call centers were evacuated, so there was no one to answer the call if it did get through. All the carriers I asked replied their systems worked. I'm trying to figure out if these were isolated problems or widespread. How well did your NOC-to-NOC communications work?