Pierre Marie, I am not sure what you mean by "coverage", that is, are you asking what percentage of the US market uses NTI versus AT&T equipment, or are you asking what cities and/or states are using NTI versus AT&T equipment ?
Somewhere in the early development of the RBOCs, different companies decided to buy their equipment from different vendors. However, over time, some of them decided to buy equipment from more than one vendor, so there is no absolute dividing along those lines. To complicate matters, the vendors have often more than one version and the buyers in their wisdom did not necessarily buy all the bells and whistles that each vendor has to offer, for each location. You are posing an interesting marketing question that I had to deal with often in my career. The vendors know what is located where, for as far as their equipment is concerned, and by now have a fair idea of where the competition's equipment is located. However, that is considered by both the vendors and the buyers as highly sensitive information because that knowledge is what is used for market shaping. They won't tell you. One can do approximations based on available public information, but that is quite a chore. You'll have to determine how badly you need that info, and how accurately you need it, before spending the money. Ciao, Vic
