Sullivan & Cromwell and Wachtell Lipton Rosen & Katz have taken lead roles on AT&T's $39bn (£24bn) purchase of T-Mobile USA from Deutsche Telekom, reports The Am Law Daily.

The cash-and-stock deal will create the largest mobile phone company in the US. AT&T has 95.5 million subscribers, while T-Mobile USA has 34 million.

Sullivan & Cromwell is advising AT&T on the deal with a team led by New York M&A partner Joseph Frumkin and Los Angeles M&A partner Eric Krautheimer. Frankfurt corporate partner Wolfgang Feuring is handling German law matters, while Los Angeles partner Hydee Feldstein is advising on financing.

The team also includes New York tax partner Andrew Mason and New York benefits/executive compensation partner Matthew Friestedt.

Deutsche Telekom has turned to Wachtell Lipton Rosen & Katz, with the elite US firm fielding a team led by corporate partners Adam Emmerich and Steven Cohen.

Other firms to have won roles on the deal include Arnold & Porter and Crowell & Moring, which are providing regulatory advice to AT&T, while Cleary Gottlieb Steen & Hamilton and Wiley Rein are also advising Deutsche Telekom.

Meanwhile, Simpson Thacher & Bartlett is advising JP Morgan and Greenhill as financial advisers to AT&T. The firm's team is led by corporate partner Bill Curbow alongside fellow New York partners Bill Sheehan and Frank Huck.

As part of the deal, Deutsche Telekom will receive an equity stake in AT&T, and a Deutsche Telekom representative will join the AT&T board of directors.

Initial reaction to the deal has focused on what the combination will mean for consumers and for regulators. The Wall Street Journal reports that the deal is likely to be of "particular concern to antitrust enforcers because the industry's two dominant companies – Verizon Wireless, a joint venture of Vodafone Group PLC and Verizon Communications, and AT&T – are already so far ahead of anyone else, raising the spectre of an effective duopoly in mobile telephony."

The deal is expected to close in "approximately 12 months," the companies' statement said. Should the deal not go through, AT&T has agreed to a $3bn (£1.8bn) breakup fee.

The Am Law Daily is a US affiliate title of Legal Week.