It was through Essentials Consulting that AT&T retained Cohen.
Stephenson's note followed the revelation that the company had paid Cohen $600,000 to advise on the $85.4 billion merger with Time Warner and other regulatory matters.
Quinn started with the Bell system as an operator for Illinois Bell in 1980, before AT&T was broken up by the Justice Department in a landmark antitrust action four years later.
He was correct. past year his administration sued to block AT&T's merger with Time Warner.
Makan Delrahim, the chief of the Justice Department's antitrust division, for his part has argued the government's position is the deal would "mean higher monthly television bills and fewer of the new, emerging innovative options that consumers are beginning to enjoy".
AT&T noted in the fact sheet that Cohen was among "several consultants" the company hired as Trump was assuming the presidency.
In addition to AT&T, Avenatti's document revealed details of payments to Cohen's LLC from Korea Aerospace Industries, the global health care firm Novartis AG, and Columbus Nova, a NY investment firm run by Andrew Intrater, a cousin of Russian billionaire Viktor Vekselberg.
The FBI raided Cohen's home and office in April, as part of a probe being conducted by NY federal prosecutors.
At the time that AT&T engaged Cohen, it wasn't aware of "the current controversy surrounding Cohen", AT&T said.
"To be clear, everything we did was done according to the law and entirely legitimate", Stephenson wrote.
AT&T may have approached other Trump allies for information around the time it paid Cohen, The Daily Beast says, including the firm of former Trump campaign manager Corey Lewandowski. CEO Vas Narasimhan said in a letter to employees on Thursday that the company "made a mistake" in retaining Cohen.
Indeed, in addition to the scandal surrounding Cohen, the Trump administration has often had the look of a feeding frenzy, with Trump and those around him facing frequent accusations of attempting to profit from his presidency.
Essential Consultants was the same company Cohen used in October 2016 to route money to Daniels in exchange for her agreement not to disclose an alleged affair with Trump.
An attorney for Cohen did not immediately respond to a request for comment. Quinn declined to comment.
Wyden is seeking the contracts between Novartis, Cohen and his firm Essential Consultants; more details about the payments; and documents showing how the deal was approved inside the drugmaker and who was involved in that process.
Following Avenatti's release of information on Tuesday, AT&T and Novartis each revealed that the companies had been contacted by Special Counsel Robert Mueller's office in late 2017 about their respective arrangements with Cohen.
Cecilia Kang is a New York Times writer. The companies were not allowed to pursue that line of argument during the trial, but they may try to use it should they lose the case and appeal.
Government ethics lawyer Kathleen Clark said Cohen had an obligation under NY state law to inform Trump of the consulting work if it potentially conflicted with Cohen's work as a personal lawyer to the president.