If AT&T (T 0.06%) wants to upgrade its network at a cost of $14 billion, and raise its share price with up to $11 billion in stock buybacks, and buy second-tier wireless operator Leap Wireless, and go on a shopping spree in Europe in order to keep up with rival Verizon's (VZ 0.25%) latest monster deal, then it's got to start raising some cash -- pronto.

Source: Justin Smith/Wikimedia Commons, CC-By-SA-3.0.

According to Bloomberg's unnamed sources, AT&T is hoping to rake in up to $5 billion by selling off its cell towers to possible buyers such as American Tower (AMT -0.39%), Crown Castle International (CCI 0.35%), and SBA Communications.

If AT&T does sell off its towers, it wouldn't be the first mobile operator to do so lately, as tower operators continue buying up available wireless infrastructure. Earlier this month, American Tower announced its agreement to acquire 100% of Global Tower Partners from parent company MIP Tower Holdings for $4.8 billion.

American Tower said it would purchase Global Towers' 5,400 towers with $3.3 billion in cash and borrow the rest. That acquisition would increase American Tower's infrastructure holdings by around 25%.

And In September of last year, Crown Castle agreed to buy the rights to 7,200 T-Mobile towers for $2.4 billion in cash. That deal gave Crown Castle approximately 30,000 domestic towers, making it the largest wireless infrastructure operator.

By selling its towers, AT&T would be losing about $326 million annually from renting out space on its approximately 10,000 towers to other wireless companies, according to Bloomberg. However, the company would likely work out a leaseback arrangement with whichever company or companies end up with the towers.

Verizon has had to do some cash-raising itself in order to complete its proposed buyout of Verizon Wireless partner Vodafone (VOD -0.12%). Verizon recently made a public offering of $49 billion worth of notes to help it pay the $58.9 billion in cash it needs to give Vodafone as part of the $130 billion price tag for sole ownership of Verizon Wireless.

That's quite a gulp, but it will almost double Verizon's domestic mobile revenue, and, as AT&T found out with its failed acquisition proposal of two years ago, the regulatory agencies don't want to see a consolidation of the major wireless operators in the U.S.

The FCC and the DOJ shot down AT&T's $39 billion attempt to acquire T-Mobile because of strong antitrust fears. That means significant acquisitions for AT&T would have to happen overseas, most likely in Europe.

So Vodafone, the largest European mobile operator, may also play a part in any AT&T expansion. By selling off its Verizon Wireless stake, it makes itself more affordable as a buyout target. The cost for Vodafone has been estimated at around $124 billion according to one analyst who talked to Businessweek. Certainly not cheap, but doable -- maybe.

Other potential European buys could include EE, the U.K. mobile carrier that's a partnership of Deutsche Telekom and Orange, and some assets of Spanish company Telefonica (TEF 0.48%).

Meanwhile, back home, Leap stockholders will get a chance to vote at a special meeting Oct. 24 on whether or not to accept AT&T's buyout offer. If they vote "Y, then that's another $1.19 billion AT&T will have to come up with.