Three of Africa’s largest telecommunication tower companies plan to pursue share sales in either London or New York early next year, taking advantage of high industry valuations to fund expansion, according to people familiar with the matter.

Closel-held IHS Towers, targeting an enterprise value of $10-billion, plans to list in New York, said the people, who asked not to be identified as the information was not public. Helios Towers Africa is looking at a valuation of at least $2-billion, while Eaton Towers is aiming for about $2-billion, the people said. Both will list in London, while Eaton is also considering a secondary listing in Johannesburg, they said.

Africa’s phone mast industry is booming, as rising wireless device use leads to a leapfrogging of traditional land-line connections. Mobile subscriptions in sub-Saharan Africa are set to surge 41% to 990-million in five years, according to Ericsson AB. Tower operators, which also sell power to remote sites in Africa, are looking to build new masts and buy existing ones from carriers such as MTN Group and Vodacom Group.

The planned stock sales are being timed to line up with robust interest among investors for the stable returns and growth offered by tower companies, which host equipment for carriers on their masts. Tower operator shares are near record highs globally, with many making acquisitions as phone companies offload infrastructure. Spain’s Cellnex Telecom has gained 52% this year and American Tower is up 39%.

“There is strong demand for tower company assets and, similarly, investor appetite for emerging market telecom businesses,” said Laura Graves, MD for Africa at TowerXchange, a networking and advisory group for the towers industry. She said she expects IHS Towers, Helios and Eaton to each list about half of their share capital to bring in new investors.

The African tower companies have each appointed banks and advisers and are meeting with potential investors to test interest, said the people. IHS has hired Goldman Sachs Group, Citigroup and Morgan Stanley; Helios Towers is working with Standard Bank Group, Bank of America Merrill Lynch and Credit Suisse Group; and Eaton Towers is working with JPMorgan Chase and UBS Group.

Representatives for IHS Towers, Helios and Eaton declined to comment. Credit Suisse, UBS, BAML and Standard Bank declined to comment, while the rest of the banks did not respond to requests for comment.

IHS is part-owned by Johannesburg-based MTN, French investment firm Wendel SA and Goldman Sachs & Company Millicom International Cellular SA, which has mobile-phone operations in Latin America and African countries including Tanzania, and owns a stake in Helios. Eaton is part-owned by Ethos Private Equity.

Helios Towers said in September that it was exploring strategic options, including a potential listing on the London Stock Exchange, though no final decision had been made. IHS Towers told Bloomberg last year that it would look to New York and London for a possible listing.