Bharti Airtel is expected to reach an agreement on the sale of its telecom towers in Nigeria for more than $1 billion within the next three weeks.

American Tower Company (ATC) is believed to be leading the race to buy the 4,000 towers, followed by IHS Towers, said a person aware of the status of talks.

The Economic Times of India reported that once the sale goes through, Bharti would have successfully sold almost half its towers in Africa.

“ATC is believed to have bid the highest amount,” said the source. While ATC didn’t respond to ET’s query, IHS couldn’t be reached for comment. The proceeds of the sale will be used to retire a part of the company’s debt, which dropped to $9.6 billion at the end of the June quarter from $10.07 billion at the end of March.

Bharti’s net debt-to-EBITDA dropped to 2.04 from 2.20 between the two quarters. The development comes close on the heels of Bharti selling 3,100 towers in the continent in July.

Bharti had sold its 3,100 towers to Helios Tower Co, an independent tower operator backed by George Soros, Madeleine Albright and Jacob Rothschild, for an undisclosed amount.

While neither Bharti nor Helios disclosed the valuation of the transaction, a person aware of the details told ET that the Indian company had raised close to $800 million.

As Economic Times reported previously, Bharti is hoping to raise up to $3 billion through the sale of its African towers.

However, given the current valuation of tower companies in the continent, Bharti’s expectation is believed to be on the higher side. “Since buyers are (only) willing to cough up some more than $2 billion, negotiations are delaying the closure of the deal,” a person close to the development told Economic Times  .

Bharti owns 15,000 telecom towers across 17 countries in Africa. It decided to sell them to independent tower companies after failing to create a joint venture tower company with other telecom operators.

This would have been along the lines of Indus Towers, a joint venture of Bharti, Vodafone and Idea Cellular in India.

Increasingly, telecom operators across Africa such as MTN are selling their towers to independent companies owing to the high costs of running the infrastructure in areas of low population density. These operators then lease the towers back from the buyers on a long-term basis.

The purchase makes business sense for tower companies such as ATC and Goldman Sachs-backed IHS, which are then able to rent them out to multiple telecom service providers.