Too late to edit my previous post without bothering an administrator.
I knew she was safe because I talked with her shortly after the attack, but we had no direct communication for over 12 hours afterward. She had a cell phone, but the cell phone towers in Manhattan were on the top of one of the towers and there was no such thing as a smart phone in 2001. Yes, there were pay phones, but even if they were functional the lines to use them were ridiculously long and most peoples' priority was figuring out how to get home. I did get an indirect update about her around 7 PM. What people were doing was calling a loved one and giving them a list of other people to call to let those folks, like me, know what their loved ones' were status was regarding getting of the island.
When I underscored extremely in my last post it was because she was supposed to be at an industry conference at Windows on the World, which was the restaurant on the 110th floor of one of the towers, but having gone for many years in a row declined at the last minute that year. All of her professional friends and colleagues who attended, and my many tried to persuade her to go again, died.