Mexico sold Telmex control to Slim's group in 1990, and the network was rebuilt

Mexico's telephone service, run by the state-owned Teléfonos de México from 1972, was a national embarrassment by the late 1980s: new customers waited up to three years for a line, Mexico had just 4.9 lines per 100 people in 1989, and eight of ten homes had no telephone. The government had been skimming the company's profits to fund the budget, leaving it short of investment.

In December 1990, as part of an eight-year privatization drive, the state sold 20.4 percent of Telmex's stock and voting control for $1.76 billion to a consortium led by Carlos Slim's Grupo Carso, with Southwestern Bell and France Télécom. The structure gave the buyers 51 percent of the voting shares, so management control — not just an ownership stake — changed hands.

The new owners modernized relentlessly. By 2000 roughly $17 billion had been invested in the sector: fixed-line penetration climbed from 6.4 to 10.6 lines per 100 people, the average wait for installation fell from two years to 25 days, and the network became fully digital. Follow-on offerings in 1991 and 1992 raised a further $3.7 billion for the state as its stake shrank to nothing by 1994.

The 1990 sale raised $1.76 billion for control; by 2000, $17 billion invested, line density rose 6.4 to 10.6 per 100, waits fell from two years to 25 days.

Selling a controlling stake, not just shares, gave the buyers both the incentive and the authority to invest in a network the state had starved.

The buyers brought what the state company lacked: hard currency plus Southwestern Bell's operating experience and France Télécom's technology.

A tax break tied to reinvestment steered cash into the network instead of the treasury.

Staged global offerings let the government monetize its remaining stake as the turnaround progressed.

Sell control, not just shares, and tie the sale to an investment plan: owners with cash and technology turned a starved monopoly into the engine of a national build-out.

Telmex kept its dominant position into the 2000s and Carlos Slim built one of the world's largest fortunes largely on its cash flows. The sale is still the benchmark of Mexico's privatization drive — it raised money, modernized infrastructure and created a private champion — even as critics later pointed to the monopoly protections that made Telmex so profitable.