UPDATE 1-Trades in 3Com, ahead of HP deal news, turn heads

* 3Com call option volume surges ahead of proposed deal

* 3Com $5 call options stand out as shares rise

* 3Com shares up 35 pct at $7.69 after the bell (Adds details of options trades, analyst comments, paragraphs 11, 15-17)

By Doris Frankel

CHICAGO, Nov 11 (Reuters) - A jump in 3Com Corp (COMS.O) shares and call options on Wednesday before a $2.7 billion offer for the company was announced sparked talk that the news had been leaked, option traders and analysts said.

Hewlett-Packard Co (HPQ.N) announced the deal to buy the network equipment maker after the closing bell on Wednesday.

At first glance, option traders said, the hallmarks of suspicious trading were there: shares of 3Com jumped 28 cents, or 5.18 percent, to $5.69 during the day, rising from the opening bell and closing a penny off the high of the day.

After the bell, 3Com shares shot up about 35 percent at $7.65.

Option market sources said it wasn't just the stock behaving oddly ahead of the late afternoon news. Volume in 3Com call options -- which convey the right to buy the company's shares at a fixed price within a specified time period -- soared.