Dan Borislow, whose MagicJack, peddled in television infomercials, helped pioneer free phone calls through the Internet, died July 21 in West Palm Beach, Fla. He was 52.

His death was confirmed by Brad Shewmake, a spokesman for MagicJack Vocaltec, the maker of the device. Mr. Borislow was the founder and former chief executive officer of the company, based in Netanya, Israel, and West Palm Beach.

He died after a heart attack after playing in a soccer game in West Palm Beach, according to an e-mail today from his friend Douglas Kass, founder of Seabreeze Partners Management in Palm Beach.

The company has sold more than 10 million MagicJack units, which connect to a computer’s USB port or router to enable voice calls over the Internet, according to its Web site. More than 25,000 retail stores sell the item.

Gerald Vento replaced Mr. Borislow as the company’s chief executive on Jan. 1, 2013.

Though calls are free, the product isn’t: The latest version, the MagicJack Go, retails for $59.95, plus $35 for annual service after the first year, according to the company’s website.

The device was promoted mostly in television infomercials. “Introducing MagicJack,” said one, “the breakthrough device that makes your monthly phone bills disappear.”

In a recent interview with Bloomberg News, Mr. Borislow said his invention was borne from desperate times:

“I had a smartphone-like idea, in 2004,” he said. “And I tried like hell. At the time, it was a WiFi phone. We went to Taiwan to where the experts on WiFi were at the time, and we tried — we must have had 30 prototypes of phones. I just couldn’t make what would turn out like a smartphone.

‘‘So I had $13 million invested of my own money, I had built up a hell of a telecom network while we were trying to make this Wi-Fi phone work — it was costing almost $1 million a month. So I had to come up with an idea, and fast, and really, out of desperation, I came up with the MagicJack.’’

A thoroughbred horse owner and racer, Mr. Borislow won $6.7 million in May by predicting the winners of six races at Gulfstream Racing & Casino Park in Hallandale Beach, Fla. The winning ticket was part of $15,206 in bets Mr. Borislow made on the track’s Rainbow 6 betting promotion, according to a report in the Daily Racing Form.

Daniel Borislow was born Sept. 21, 1961, in Philadelphia, according to the National Thoroughbred Racing Association.

His interest in innovation started when, as a 12 year old, he acquired a fast lawn mower that enabled him to cut more grass at lower prices than his neighborhood competitors, according to a 2008 profile in the magazine of Widener University, his alma mater.

He received a bachelor’s degree from Widener, in Chester, Pa., in 1984, according to the school, which named him to its Board of Trustees.

Before MagicJack, he was the founding chief executive of Tel-Save Holdings, a long-distance telephone-service provider then based in New Hope, Pa., which he took public in 1995.

In 2011, Mr. Borislow bought the Washington Freedom, a team in the Women’s Professional Soccer league. He renamed the team MagicJack and moved it to Boca Raton, Fla. Mr. Borislow feuded publicly and in court with the league, which folded in 2012.

Survivors include his wife, Shelly; two children; his parents; and three brothers, the Palm Beach Post reported.