I think it is also critical (in that constellation) that AT&T controls the biggest Backbone of the US. Here's a citation from a letter:
"AT&T owns and operates the largest Internet backbone in the United States and one of the largest worldwide. According to AT&T itself, “AT&T carries more combined data, voice, and Internet traffic than any other carrier in the U.S.: 675 trillion bytes (terabytes) and 300 million voice calls (average day).”1 SBC is the second largest wireline provider of local, long distance, voice, and data services in the United States. SBC also has controlling interest in the nation’s second largest wireless carrier. AT&T’s backbone is the largest Multi-Protocol Label Switching (“MPLS”) network. MPLS enables the network operator to prioritize packets, providing superior performance over the ordinary method of routing Internet traffic, which requires routing table look-ups for all packets routed.2 MPLS has a lower latency rate (the amount of time it takes a data packet to travel roundtrip between two points in the network) and packet loss rate than ordinary Internet routing. Thus, MPLS networks have a big advantage over “ordinary” Internet backbones."
http://www.comptelascent.org/public-...aug10_2005.pdf
If it is true that AT&T give the NSA access to this data which they deliver, they could do much more with data mining tools and enough computing power than they had ever been able to do before. This read is interesting:
http://www.wired.com/news/technology/0,70621-0.html