BlackBerry maker Research In Motion has hired law firm Milbank, Tweed, Hadley & McCloy LLP to work out a restructuring plan that could include selling assets, seeking joint ventures or licensing patents, people briefed on the matter said.

As part of the struggling Canadian smartphone maker's strategic review, the RIM board is discussing ways to boost revenue from its new BlackBerry 10 operating system and possibly opening up its proprietary network, the sources said.

At one point, RIM was hoping to add as much as $4 billion in revenue from deals with major telecom carriers, sources said.

"This is a very mature strategy and RIM was very far down the road with a lot of those discussions with carriers," one of the sources added.

The restructuring efforts come as the Blackberry maker tries to stem customer losses to Apple Inc's iPhone and smartphones running Google Inc's Android software.

RIM posted a $125 million loss in its most recent quarter as it wrote down BlackBerry inventories. It took an even larger hit on its underperforming PlayBook tablet computers three months earlier.

RIM's stock has plunged 75 percent in the last 12 months, giving the company a market value under $7 billion. Representatives for Milbank and RIM declined to comment.

A number of investment banks have approached RIM over the past several months, vying for a role as financial adviser.

But for now, RIM is not expected to hire a banker unless it decides to sell off a major asset or if the company receives takeover interest from an industry competitor, the sources said.

RIM has worked with Milbank previously and also retains law firm Skadden, Arps, Slate, Meagher & Flom LLP and the consulting firm Monitor Group for strategic advice. The two firms were not immediately available for comment.

BALSILLIE'S PROPOSAL
RIM, which once dominated the smartphone market, appointed a new CEO, Thorsten Heins, in January when longtime co-CEOs Mike Lazaridis and Jim Balsillie resigned under pressure.

Before he left, Balsillie had led a three-pronged plan to double RIM's service revenue by allowing carriers to use its services for messaging, content delivery, and analytics on all smartphones, sources with knowledge of his plan told Reuters.

Balsillie's plan offered carriers a way to tempt budget customers to upgrade to smartphones, with a data plan restricted to social networking and messaging services.

The sources said it also involved a 'carrier cloud' to compete with device-specific services such as Apple's iCloud and cross-platform products, like DropBox and Netflix.

RIM started talks with the world's largest telecom companies more than six months ago and they were still going on as late as January at the Consumer Electronics Show in Las Vegas.

But the board got cold feet on concerns about cost and fears that the company's smartphones could lose more market share if the popular BlackBerry Messenger chat system was available on other devices. Balsillie quit RIM's board in March.

Sources declined to discuss pricing details for the aborted plan, citing the potential for deals to still get done.

It was not clear how much of Balsillie's plan will be incorporated in the restructuring that Milbank is advising on.

STRATEGIC ACQUISITIONS
Since late 2010, RIM had been taking steps to make its network services available to other devices, and made a string of acquisitions to support that strategy, according to several sources with knowledge of the matter.

Last October, RIM bought Dublin-based digital content company Newbay Software, which stores photo and video albums, music, address books, calendars on its own servers and can deliver it to any Internet-connected device, including mobile phones, personal computers, tablets and televisions.

When RIM bought it, Newbay boasted more than 80 million subscribers and had relationships with many of the carriers that Balsillie was negotiating with.

Earlier in 2011, RIM bought small Swedish video-editing company Jaycut, German social gaming company Scoreloop in June, and Waterloo-based tinyHippos, which owned a cross-platform app testing tool.