UPDATE: 2/12/13, 8:20 p.m. EST. Information on the outside lawyers for Charter Communications has been added to the seventh paragraph of this story.

Cablevision Systems announced Friday that it has agreed to sell regional cable provider Optimum West to Charter Communications for $1.63 billion in an all-cash deal.

Acquiring Optimum West, a Cablevision unit with roughly 360,000 subscribers in the Rocky Mountain region, will allow St. Louis–based Charter to establish the presence in the western U.S. it has sought for some time. Charter snagged the Cablevision subsidiary after topping rival bids by such companies as Suddenlink Communications and Time Warner Cable, according to Bloomberg.

Sullivan & Cromwell M&A partner Duncan McCurrach, tax partner Davis Wang, finance partner Robert Downes, environmental special counsel Matthew Brennan, and IP special counsel Spencer Simon are leading the team from the firm that is advising Bethpage, New York–based Cablevision on the matter. S&C associates Siaw Ching Lee, Matthew Glick, Brian Jebb, Stephen Miller, Julie Newman, Anca Paraian, Kevin Salinger, and Ashish Thaker are also working on the deal.

Cablevision is a longtime S&C client. They advised the company in connection with its $1.36 billion purchase of Bresnan Communications—the predecessor to Optimum West—from private equity firm Providence Equity Partners in 2010.

S&C also served as antitrust and finance counsel to Cablevision on its $650 million purchase of Long Island–based newspaper Newsday in May 2008, as well as the company’s nearly $500 million purchase of the Sundance Channel through its Rainbow Media subsidiary that same month. Two years later Cablevision spun-off Rainbow Media, which was renamed AMC Networks in 2011.

Cablevision’s general counsel is David Ellen, while Victoria Salhus serves as the company’s deputy general counsel and corporate secretary. Zachary Carter, a former U.S. attorney for the Eastern District of New York and current Dorsey & Whitney partner, is an independent member of Cablevision’s board of directors.

Gregory Ramos, an corporate and telecommunications partner with Sherman & Howard in Denver, is serving as M&A counsel to Charter Communications for its purchase of Optimum West. Kirkland & Ellis debt finance partner Jason Kanner in New York is providing finance counsel to the company for the transaction.

Saddled with $21 billion in debt, Charter filed for bankruptcy in March 2009, just a month after settling a $150 million malpractice suit against its former lawyers at Irell & Manella over the company’s $3.1 billion buy of Bresnan Communications—a cable company with operations in the Midwest with ties to the predecessor of Optimum West—in 1999. Terms of the settlement with Irell were not disclosed. (Cable pioneer William Bresnan, the one-time owner of both Bresnan entities, died in 2009; one of Bresnan’s daughters is involved in a high-profile divorce from New York Yankees general manager Brian Cashman.)

Kirkland advised Charter as it emerged from bankruptcy in November 2009 under a plan that saw a stake in the company held by Microsoft cofounder and billionaire Paul Allen—who was advised in the matter by Skadden, Arps, Slate, Meagher & Flom—reduced from 91 percent to 35 percent, according to our previous reports. (Forbes reported last year that Allen, who bought Charter for $4.5 billion in 1998, has finally started to make money from the company.)

Charter general counsel Richard Dykhouse and senior counsel Connie Kovach are leading an in-house team from the company working on the Optimum West deal. Former Patton Boggs partner Robert Quicksilver, who returned to his hometown of St. Louis to work for Charter in September 2011, serves as chief administration officer for Charter.

Bruce Karsh, a former attorney at O’Melveny & Myers who went on to become a billionaire after cofounding Los Angeles–based asset manager Oaktree Capital Management, serves as an independent member of Charter’s board, along with Craig Jacobson, a founder of Beverly Hills–based Hansen, Jacobson, Teller, Hoberman, Newman, Warren, Richman, Rush & Kaller.

Charter’s purchase of Optimum West from Cablevision is expected to close in the third quarter of 2013, pending regulatory approvals.