Us prosecutors played the first wiretaps yesterday of phone conversations between New York hedge fund billionaire Raj Rajaratnam and Rajiv Goel, a key government witness.

In the tapes, Goel, a former Intel executive, feeds Rajaratnam details of Intel’s $1 billion investment in a joint-venture between Clearwire and Sprint in 2008 to build out a global 4G platform.

Rajaratnam, on trial for insider trading, quizzes Goel about the investment team involved months before it was publicly announced, the tapes show. They also openly discuss that investors agreed to put as much as $3.5 billion in the transaction, code-named “Project Rain.”

The defense argued that rumors of a potential investment by Intel and others were swirling about before the deal was official.

Goel, Rajaratanam’s pal, is expected to take the stand today.