It's one of the perennial questions in telecom: How and when will Verizon Communications Inc. (NYSE:VZ) and Vodafone Group plc (NASDAQ:VOD) unwind their highly successful, incredibly valuable wireless joint venture?

Verizon would like to own all of Verizon Wireless. Shareholders of Vodafone have longed to see cash from their shares in the JV, which has not paid a dividend for years.

These wishes consistently run into the financial constraints of the partners.

Now, Goldman, Sachs & Co. (NYSE:GS) analyst Jason Armstrong is positing a creative solution, suggesting that Verizon could model a buyout on Comcast Corp.'s (NASDAQ:CMCSA) purchase of a controlling stake in NBC Universal. There, debt taken out by NBCU and cash flow that the unit generates will finance a significant part of the deal.

"We believe an NBCU-like structure, whereby Verizon uses debt capacity and free-cash generation of Verizon Wireless to take out Vodafone's stake over a multi-year period of time, may provide an optimal solution," Armstrong wrote.

The analyst values the mobile joint venture at 7.5 times Ebitda, based on Verizon Wireless' purchase of Alltel Corp. and AT&T Inc.'s (NYSE:T) buyout of Centennial Communications. Vodafone's minority position would be worth $92.5 billion, based on Armstrong's Ebitda projections for early 2011. As part of its payments, Verizon could include its stake in Italian operator Vodafone Omnitel NV, which Armstrong values at $6.6 billion. By the Goldman Sachs timetable, Verizon could complete the deal by 2015.

All right, but what about the timing? Arguably, Verizon Wireless is at a disadvantage relative to AT&T, which wholly owns its wireless arm. AT&T can consolidate corporate costs and more fully integrate the business with its other units.

Still, one industry watcher believes that "[t]here is nothing from this quarter" that suggests greater pressure on Verizon to repurchase the stake. "There really is just a systemic difference" between Verizon and AT&T, he said. "We don't see anything near term there."

Armstrong suggests that a projected shortfall in Verizon's ability to support its dividend in the second half of 2011 could motivate the carrier. Structuring a deal with Vodafone, he suggests, would solidify its ability to cover the payouts.

Verizon paid investors $5.4 billion in 2009 dividends. The company boosted the dividend 2.6% in September.

Verizon CFO John Killian was adamant that the telecom is fully able to cover its dividend in an Oct. 22 earnings call.

"The cash generation of that business is not going to decelerate. If anything, it is going to accelerate," he said. "We are in a very good position from that perspective. We believe the Verizon dividend is extremely safe."

Verizon Wireless does not pay its parents a dividend, but last year paid Verizon and Vodafone $3 billion to help cover taxes.

Even without a wireless dividend, Verizon's cash flow from operations totaled $16.9 billion in the first half of 2010, compared to $14.1 billion in the first half of 2009.

With a 55% stake in the JV, Verizon controls the wireless company's board. If it needed more cash to cover its dividend in the latter half of 2011, the telecom could resume Verizon Wireless' dividend payments.

So a buyout may not be in the cards anytime soon.

Nonetheless, questions about whether Verizon and Vodafone will unwind their partnership will persist until one day the telecoms announce that they are unwinding the partnership.

The success of Verizon Wireless, and the massive price that Verizon would have to pay, has been an enduring impediment. Armstrong's proposal could form the basis of a solution.