“This is a partnership, not a contractual relationship.” [1]
"Because of partner relations and legal authorities, SSO Corporate sites are often controlled by the partner, who filters the communications before sending to NSA." [2]
[1] https://www.nytimes.com/2015/08/16/us/politics/att-helped-ns...
[2] https://www.nytimes.com/interactive/2015/08/15/us/documents....