GettyImages-Warren Buffett
Berkshire Hathaway's CEO Warren Buffett (L) and his business partner Vice Chairman Charles Munger at a news conference on May 4, 2003, in Omaha, Nebraska. Photo by Eric Francis/Getty Images

When a top investor in Apple stock says he does not use an iPhone, it is bound to be a big surprise!

That is what billionaire investor Warren Buffett did when he revealed the secret that he is not using an iPhone and is too happy with his $20 flip phone.

Buffett’s Berkshire Hathaway owns 5.5 percent of Apple stock and iPhone accounts for the lion share of the company's revenue.

The billionaire's spartan $20 flip phone is a Samsung SCH-U320 that is selling at 20 to 30 dollars on eBay.

According to Forbe’s billionaire, he lacks hands-on experience with the iPhone although he is good at using an iPad to do research and stock price updates.

Buffett also showed off his flip phone during a talk at The Gatehouse's Hands Up for Success luncheon.

“Here's my phone, incidentally. Alexander Graham Bell lent it to me and I forgot to return it,” Buffett joked.

Buffett also said he was gifted an iPhone X but he has not set it up yet.

"A fellow sent me a '10' the other day, but I'm not using it yet," Buffett said.

The investor has acknowledged that his interest in Apple shares was not driven by its lure of finances, but he likes the strong brand equity and ecosystem of Apple.

That is why Buffett’s reaction to Apple’s recent foray into entertainment was considered significant. He said Apple can afford a “mistake or two” while commenting on its entry into new markets including entertainment.

Buffett counsels discretion on buying new IPOs

Meanwhile, Warren Buffett cautioned regular investors against buying hot offerings in a "hot market." Case in point was the likes of highly chased Lyft IPO and a plethora of upcoming offerings from Silicon Valley's startups.

Noting that he has never bought an IPO after the 1950s, Buffett recalled buying Ford Motor's share offering when it was making a debut in the market.

Many deal offerings are expected this year from Silicon Valley's unicorns. In the tech industry, unicorn refers to a company that has a valuation of $1 billion-plus even before it goes public.

The billionaire investor's advice to regular investors is that “buying new offerings during hot periods in the market ... I don't think it's anything the average person should think about at all.”

Buffett told a CNBC anchor that his view on the matter may also inhibit people from getting a slice of successful companies like a young Amazon or Uber.

But Buffett said his counsel on the matter is --"be safe than sorry" when it comes to investing in untested companies.

“You can go around making dumb bets and win. ... It's not something you want to take as a lifetime policy,” he quipped.