By David Russell, reporter at OptionMonsterNEW YORK -- The bulls targeted Vodafone ( VOD) for the second session in a row Tuesday. OptionMonster's tracking programs detected unusual activity in the July 28 calls. More than 12,000 contracts traded against previous open interest of 1,746, indication new positioning, with most of the volume pricing for 50 cents. These calls lock in the price where the shares can be bought. They can generate some nice leverage from a modest gain in the stock but also can expire worthless if it doesn't move. Vodafone shares fell 1.24% to close at $26.21 Tuesday but climbed late in the session after the calls hit. In the previous day, traders snapped up the February 27 calls, looking for a shorter-term pop. Shares rose in London Tuesday after Verizon CEO Lowell McAdam told The Wall Street Journal that he might be interested in buying Verifone's 45% stake in Verizon Wireless. Total option volume was 10 times greater than average in the British company, with calls outnumbering puts by a bullish 5-to-1 ratio. Russell has no positions in VOD.