Weil Gotshal & Manges and Sullivan & Cromwell have landed the headline roles on the $49bn (£29bn) merger between telecommunications giant AT&T and pay-TV company DirecTV.

The stock and cash deal – one of the largest M&A transactions so far this year – is expected to close in mid-2015, and is the latest in a series of blockbuster telecommunications deals providing work for US firms.

AT&T has instructed go-to corporate adviser Joseph Frumkin for the deal, with Sullivan's New York-based M&A managing partner working alongside Los Angeles corporate partner Eric Krautheimer.

The other Sullivan partners on the deal include Andrew Mason (tax) and executive compensation and benefits specialist Matthew Friestedt. Special counsel Spencer Simon also advised on intellectual property matters.

Frumkin and a number of partners in the team have previously advised the company on mega-deals including AT&T's $86bn (£51bn) stock-for-stock acquisition of BellSouth, its $1.2bn (£713m) cash purchase of Leap Wireless, and its private $2.4bn (£1.4bn) acquisition of Alltel wireless properties from Verizon.

Arnold & Porter is also providing regulatory and competition advice to AT&T in the US and Latin America. Washington DC partner Richard Rosen and London partner Susan Hinchliffe are leading a team that includes Maureen Jeffreys and Wilson Mudge in DC and London-based Mike Ryan.

AT&T has instructed a string of other firms for the deal, including Crowell & Moring, Sidley Austin Gibson Dunn & Crutcher and Kellogg Huber Hansen Todd Evans & Figel, Reuters has reported.

Meanwhile, DirecTV has instructed a New York-centred Weil team headed by the firm's transactions co-chair Fred Green and senior corporate partner Mike Lubowitz, both of whom acted on the company's $25bn (£14.9bn) merger with Liberty Entertainment in 2009.

Other Weil lawyers advising DirecTV include technology and IP partner Jeffrey Osterman, employee benefits partner Paul Wessel, employment law counsel Lawrence Baer, tax partners Marc Silberberg and Chayim Neubort, capital markets partner Matthew Bloch, environment partner Margaret Connelly and banking and finance partner Andrew Yoon.

The target company is working with Jones Day and Wiltshire & Grannis, Reuters said.

The deal follows the proposed $45bn (£27bn) merger between US cable operators Comcast and Time Warner Cable, which is currently undergoing reviews from regulators. The deal has seen mandates for Paul Weiss Rifkind Wharton & Garrison, Skadden Arps Slate Meagher & Flom, Davis Polk & Wardwell and Willkie Farr & Gallagher.