UPDATE 2-America Movil qtrly net jumps, gets China loan

* Q1 net jumps 18.7 percent

* 186.6 mln wireless subscribers through March

* Mexico, Brazil lead client additions

* Gets $1 bln, 10-year loan from China Development Bank (Recasts, adds details, credit line)

MEXICO CITY, April 28 (Reuters) - America Movil, the largest cellphone operator in Latin America, beat expectations again with a 18.7 percent rise in quarterly profit and said it had secured $1 billion in credit to improve its network.

America Movil (AMXL.MX) (AMX.N), controlled by Mexican billionaire tycoon Carlos Slim, said on Tuesday it earned 16.4 billion pesos ($1.15 billion) in the January-March first quarter, compared with 13.8 billion pesos a year earlier.

The results beat analysts' expectations of net earnings of 15.199 billion pesos.

Quarterly revenue, boosted by data and postpaid contracts, rose 15.4 percent to 93.8 billion pesos, driven by 3.9 million subscriber additions, mostly from Mexico and Brazil.

The company, which has operations from the United States to Argentina and competes regionally with Spain's Telefonica (TEF.MC), ended March with 186.6 million clients.