America Movil, which analysts estimate may have added another 4.7 million mobile subscribers in the January-March period, absorbed Net Servicos earlier this year.

"We believe that its impact on overall market sentiment toward America Movil's Brazilian operations may have a positive twist," Santander analysts Valder Nogueira and Bruno Mendonca said in a report.

"A good performance from Net in the first quarter 2012 could help ease, not solve, concerns about the Brazilian mobile business, one of investors' main pushbacks."

According to a Reuters survey of five analysts, America Movil's first-quarter net profit likely jumped 18.1 percent on average to 27.768 billion pesos ($2.2 billion) from the same period a year ago, with revenues in the period seen up 19 percent. The company is due to report earnings after markets close on Thursday.

Modifications beginning in 2012 for all Mexican companies on how commission and employee profit-sharing are recorded, bringing them into compliance with international financial reporting standards, should also help boost results.

"These accounting changes will make comparison with Brazilian peers much easier going forward, revealing stronger top line growth and reducing investors' concerns," said BBVA Research in a research note.

The company's bottom line would also get a lift from foreign exchange gains in the period -- it has operations in 17 countries outside Mexico.

ROUGH YEAR

Slim, the world's richest man according to Forbes, is coming back from a rough year in 2011, when America Movil faced tougher scrutiny from regulators - an order to lower fees helped push down annual profits by nearly 10 percent - and clashed with two powerful rivals, broadcasters Televisa and TV Azteca, as they fought for a slice of the phone market.

But analysts will take a closer look at the impact that lower interconnection fees will have on profit margins at its Mexican unit, which dominates about 70 percent of the cell phone market, with Spain's Telefonica a distant contender.

"Higher subscriber acquisition costs in both Mexico and Brazil, in conjunction with the significant adjustment in Mexico's mobile termination rates, should bring down the company's consolidated earnings before interest, tax, depreciation and amortization (EBITDA) margin," said Actinver analyst Martin Lara.

Regulators forced Slim last year to slash fees that his telecom company charged rivals in Mexico.

They also slapped America Movil's Telcel with a record $1 billion fine, although the sanction may never happen as a series of legal maneuvers from Slim's camp could end up reducing the fine to a slap on a wrist.

Competition regulators will meet again on Monday, a full year after the fine was originally ruled, to vote on whether the Slim company should be fined.

Following is a table with the expected results. All figures in pesos:

JAN-MARCH 2012 JAN-MARCH 2011 PERCENTAGE CHANGE REVENUE 185.989 bln 156.232 bln + 19.0 pct EBITDA 66.760 bln 62.104 bln + 7.5 pct EBITDA MARGIN 35.9 39.8 - 390 basis points NET PROFIT 27.768 bln 23.511 bln + 18.1 pct

(Reporting By Tomas Sarmiento and Cyntia Barrera Diaz; Editing by Muralikumar Anantharaman)

• A Permanent Economic Emergency