Sept. 25 (Bloomberg) -- Mexican mobile-phone companies could lose as many as 5 million customers under President Felipe Calderon’s budget proposals that include a telecommunications tax, carrier NII Holdings Inc. is telling lawmakers.

Lower-income subscribers wouldn’t be able to afford the service, and the decline in subscribers could slow Mexico’s economic growth, according to documents the company is providing to legislators. An NII representative confirmed yesterday that the figures were the company’s estimates.

NII, which operates the Nextel brand in Latin America, seeks to block a 4 percent tax on services such as phone calls and Internet access that would raise more than $1 billion from the industry. Calderon’s plan excludes public pay phones and rural phone lines.

“It’s probably an exaggeration to say the phone companies would lose 5 million customers,” Michael Nelson, an analyst at Soleil Securities/Nelson Alpha Research Inc. in New York, said in an e-mail. He advises buying NII shares. “If they risk losing customers by passing the tax through to their subscribers, I would expect they would eat the cost themselves.”

Mexico’s four mobile-phone companies, of which NII is the smallest, had more than 80 million subscribers at the end of June. More than 70 percent of Mexicans have a wireless phone.

America Movil SAB, controlled by billionaire Carlos Slim, is Mexico’s largest wireless carrier, followed by Telefonica SA and Grupo Iusacell SA.

NII, based in Reston, Virginia, fell 2 cents to $29.74 at 4 p.m. New York time in Nasdaq Stock Market trading. The shares have gained 64 percent this year.

To contact the reporters on this story: Crayton Harrison in Mexico City at tharrison5@bloomberg.net; Adriana Lopez Caraveo in Mexico City at adrianalopez@bloomberg.net.

Last Updated: September 25, 2009 16:10 EDT