Companies should start planning for Iran, analysts say, as the slow thawing of diplomatic relations with the country could open the door to foreign investment.



The Middle Eastern country, which has been on the receiving end of strict sanctions since its revolution in 1979, has been in political transition this year. Following presidential elections in June, hardliner Mahmoud Ahmadinejad was replaced by Hassan Rouhani who has since embarked on a series of charm offensives around the world – including a phone call last month with U.S. President Barack Obama.

Matthew Spivack, practice leader at emerging market advisory firm Frontier Strategy Group told CNBC that investors now need to start working a contingency plan for when, and if, sanctions are rolled back.



"Iran is not just about oil," he said. "FMCG (fast moving consumer goods) and healthcare companies prioritize Iran, because of very attractive demographics."



(Read More: Iran nuclear talks: the oil price fallout)



Tehran's stock exchange lists 339 companies on its website with a combined market capitalization of $104.21 billion. The country has the second largest population in the Middle East and North Africa region, according to the World Bank, with 77 million people - three times the regional average. It has the fourth biggest oil reserves in the world, according to the U.S. Energy Information Administration, and the second biggest natural gas reserves - second only to Russia.



Spivack expects Iran's public sector to attract a lot of foreign investment interest in the long term. One area ripe for Iranian government contracts would be the country's energy sector. If sanctions are lifted and Iran can start selling its oil and gas on the open market – at the moment it mainly deals with China and India – the country's energy infrastructure will need upgrading.



Sven Richter, head of frontier markets at Renaissance Asset Managers is another portfolio manager looking closely at the country. On the Tehran stock exchange the basic metals and banks are the latest sectors that are en vogue, he said, followed by telecoms.



"The stock market has the possibility of attracting attention as its relatively large and liquid and could be an interesting part of a Frontier fund," he told CNBC.



"P/E (price-to-earnings) valuations ranging between 7 times and 11 times for many of these companies look attractive."

Even business leaders are looking closer at the country. Martin Sorrell, CEO of WPP - the world's largest advertising company by revenue - included Iran in a list of frontier markets that the company was considering, adding that the "political noises" coming from the country were positive.



(Read more: The world's best performing frontier markets)



In recent months, Iran has held constructive talks with the United Nations about its controversial nuclear program. Iran and the U.S. also engaged in high-profile talks in September with President Obama speaking to Rouhani by telephone - the first direct dialogue between the two counties for over three decades.



On Thursday, the New York Times reported that Hossein Naqavi Hosseini, the deputy head of the national security and foreign policy committee, has said Iran has cut the production of enriched uranium by up to 20 percent, a move closer to one of the key demands world powers have asked of it.