Vodafone CEO Vittorio Colao says he's unsure about the future ownership of Verizon Wireless, according to an interview published in the Wall Street Journal Friday. 

Colao said he has an "open mind" when it comes to the joint venture that is Verizon Wireless. Verizon Communications currently owns 55 percent of the Verizon Wireless, while Vodafone owns a 45 percent share. 

The comments come on the heels of Verizon CEO Lowell McAdam's comments early last month, when he said that Verizon is strong enough to buy Vodafone out of its stake in Verizon Wireless. 

According to McAdam, such a buyout is "feasible" and would be made easier by the strengthening of the Verizon's wireline business. 

Verizon has long admitted to wanting to purchase the rest of Verizon Wireless via a buyout, but the business has proved too valuable for struggling Vodafone to let go. Verizon made a failed attempt to purchase Vodafone's stake in the business back in 2006.   

In the interview published today, Vittorio said Vodafone watches the U.S. situation very carefully because Verizon Wireless represents "half of our value—or whatever it is—and an important element of the Vodafone stock price."

Verizon Wireless reported 35.1 million retail postpaid accounts at the end of the fourth quarter, a 1.4 percent increase over the fourth quarter 2011, and an average of 2.6 connections per account, up 4.3 percent year over year.

Verizon has been aggressively moving customers to its LTE network, which is now available to more than 273 million people or close to 89 percent of the population in 476 markets across the U.S. Total LTE device sales increased to 7.3 million for the quarter and smartphone activations represented 6.4 million of that total. At year-end 2012, smartphones accounted for more than 58 percent of the Verizon Wireless retail postpaid customer phone base, up from 53 percent on a quarterly basis.