Businesses, especially European technology and aerospace companies, are gearing up for the possible suspension of sanctions on Iran, pending a deal being reached on that country's nuclear program by the Nov. 24 deadline. A looser sanctions regime or an outright suspension could give them increased access to a vast, lucrative market, but American companies, unlike European companies, aren't talking to their Iranian counterparts for fear of landing in a legal battle with the U.S. government -- and that caution may end up costing them.

"Iranians have by and large maintained good trade and economic ties with European countries," said Alex Vatanka, an Iranian analyst at the Middle East Institute. "Those connections are much easier to revive should sanctions be removed than for the American side, which needs to go out and recover 35 years of lost time."

Avoiding Iran because of political risks could deprive U.S. companies of billions. According to a study published in July by the National Iranian American Council, a U.S.-based organization that pushes for a peaceful resolution of differences between Washington and Tehran, the U.S. has lost out on $175 billion in export revenue from Iran between 1995 and 2012.

U.S. companies are consulting with law firms specializing in trade, many of whom are advising their clients not to engage in Iranian business dealings. One of those firms, Washington, D.C.-based Akin Gump, said in an informational document on its website that "companies that plan to test the waters with Iran ... should proceed with caution," because, among other things, the "U.S. government has pledged to engage in 'rigorous monitoring' to prevent abuse of the sanctions relief under the JPOA and to 'vigorously enforce' all other existing sanctions against Iran."

The Joint Plan Of Action, JPOA, is a deal signed by China, France, Russia, the United Kingdom and the United States plus Germany, the group known as P5+1 (the five permanent members of the UN Security Council plus Germany), that negotiates with Iran. The JPOA called for a temporary freeze of parts of Iran's nuclear program in exchange for reduced economic sanctions. The deal was signed in November 2013, and the implementation of the agreement began in January 2014. The agreement, which was set to end in July with a final deal on the future of Iranian sanctions, has been extended until Nov. 24. Before that deadline, companies from other nations have begun testing the waters.

In February, U.S. Under Secretary for Political Affairs Wendy R. Sherman told the Senate Foreign Relations Committee that foreign firms were vying to be the “first in line” to do business with Iran once sanctions were eased. French delegations have traveled to Iran to engage in commercial talks, though no official documents have been drafted yet. “As far as we have seen today, there are not deals getting done but rather people getting first in line in the hope that someday there will be a deal,” Sherman said.

U.S. trade lawyers said having business discussions with Iran is legal but is not seen favorably by the U.S. government, because it risks, in Washington's view, weakening the economic leverage the West has with Iran under the current sanctions regime. U.S., EU and U.N. sanctions have crippled parts of Iran's economy. President Hassan Rouhani, who took office in 2013, came into power with an economy that was not only suffering from sanctions but was crippled by hyperinflation caused by economic policies put in place by the government of former President Mahmoud Ahmadinejad.

U.S. technology companies could do well in Iran. Some, in fact, already have. In May 2013, the U.S. lifted a ban on sales of communications equipment to Iranians and opened access to Internet services and social media. The decision allowed U.S. companies to sell computers, tablets, mobile phones, software and satellite receivers to Iranians. Those sales were previously embargoed.

Following the easing of tech sanctions, companies such as Apple and Google opened up to Iranians. Apple began selling its Mac and iPhone range to customers planning on taking the devices to Iran and granted people residing in Iran access to its app store. Google allowed Iranians to download apps from Google Play. But Microsoft held back, apparently concerned that dealing with Iran could cause legal trouble.

Collin Anderson, an independent researcher in North Dakota, told Motherboard, "[C]ompanies are very legitimately fearful of running afoul of the sanction regimes, which are incredibly complex and very dangerous if you run afoul of them."

But the Iranian tech market is desirable. According to a Microsoft feedback platform that asked people for suggestions on new features, there is a big demand for the company's services in Iran. Users voted over 30,000 times for one of the feature suggestions, titled, "Please give the people of Iran access to the Microsoft Store." The Verge wrote that inclusion of the Persian calendar was one of the most requested features in a Microsoft poll asking for feedback on the Windows 10 operating system.

There is also a demand in Iran for U.S. games -- both video games and online games. In September 2012, Iranians were shut out from playing World of Warcraft because of U.S. sanctions. Blizzard Entertainment, a California-based video game developer, said they made the move in order to stay in compliance with U.S. law.

Some analysts have said the aerospace industry could also benefit from the suspension of Iran sanctions. Boeing and General Electric have already received licenses in April from the U.S. Treasury Department to export certain types of spare parts for commercial aircraft to Iran, whose airlines fly many American-made planes bought before the 1979 revolution that brought the end of relations with the U.S. The licenses came after the U.S. decided to implement targeted sanctions relief in January.

Richard Aboulafia, an aviation expert and Vice President of Analysis at Teal Group, said U.S. aerospace companies would not benefit significantly from the suspension of sanctions unless Iran conducted an "internal reform" of its economy. Until then, Aboulafia said, any transactions with Iran by U.S. aerospace companies will "not move the needle." He said, "Unless prices jack up, they are going to stay a second-rate economy at best."

Iran is desperate for American investment in order to rehabilitate its failing economy, Vatanka said. "Economic interest in Iran by American firms is a must for Iran to reinvigorate itself in the international mainstream economy," he said. That's part of the reason Iran may agree to a deal by the Nov. 24 deadline, Vatanka said.

Iran has pushed previously for American investment in the country. In the 1990s, the Iranian government set aside oil and gas fields specifically for U.S. exploration, but the Clinton administration ended that possibility with sanctions in 1996. Today, the Iranian government wants access to American liquefied natural gas production.

U.S. firms would be wise to listen to Iranian demand for American investment, Vatanka said. "It is a huge market. It is 80 million people that are relatively wealthy," he said. "Iran is hungry for all things American."