Iranians are besieging banks and post offices to buy the latest government issue of mobile telephone lines.
Iran is under pressure to open up its mobile network
The SIM cards providing access to the lines are in huge demand because the country has just three million lines for a population of nearly 70 million.
The cards are expensive but at $530 (£300) each they are half the cost of those available on the open market.
Some wealthy Iranians are said to be buying the new lines by the thousands and selling them on at a large profit.
At present, Iran has just one, greatly overloaded, mobile phone network, run by the state monopoly.
Even in Tehran, it can be difficult to make a call because of network overloading, say residents.
With demand for lines estimated to soar tenfold in the next five years, the government has inched open the door to private telecoms firms.
Earlier this month, a group led by Turkcell, Turkey's leading mobile phone operator, was awarded a contract to set up Iran's first non-state-owned mobile phone network.
And a third mobile phone licence is expected to be offered within two years, officials have said.
The Iranian government intends to sell two million new lines by the end of the Iranian year on 20 March which will raise more than $1bn.
The $530 price per line is approximately four times the monthly salary of a mid-ranking civil servant but more than 250,000 lines were sold in the first two days of sales which started on Saturday.
"Every morning on my way to work I see 50 or 60 people outside my local post office waiting to buy the cards," a Tehran resident told BBC News Online.
"It's cheaper to get it this way from the government than to go and get it on the open market."
The price of a line on the open market is about $1,200, residents say.
Customers are reportedly buying between 10 and 15 lines each while one man even bought 5,000 lines, according to local media reports.
Turkcell is planning to sell cards at $178 each. Its first lines are expected to start operating in 11 months' time.