BUENOS AIRES (AdAge.com) -- At a high-ceilinged former warehouse in Buenos Aires' chic Palermo neighborhood, business is humming at Santo. Argentina's ad agencies have been winning more and more international assignments, but Santo took it to a new level last year with the conquest of Vodafone's global creative account.

SANTO TOP EXECS: Sebastian Wilhelm, Maximiliano Anselmo EMPLOYEES: 35 CLIENTS: Vodafone, Coca-Cola Co., Isenbeck beer, Arnet

Maximiliano Anselmo and Sebastian Wilhelm, who opened Santo with backing from WPP in 2005, also developed a new juice brand for Coca-Cola in Latin America last year, and helped a local client launch an iTunes-like music store. For local beer marketer Isenbeck, they planned to kick off 2010 by filling an entire swimming pool with beer for Isenbeck fans to swim in, although the Argentine government intervened to nix that intriguing idea.

Maxi and Seba, as they're known, grew Santo's revenue by 25% in 2009. And that was without the buzz created at international awards shows -- Santo didn't enter any in 2009.

That's why Santo is Ad Age's International Agency of the Year, edging out the three runners-up: Canada's Sid Lee, Brazil's Almap BBDO, and DDB New Zealand.

For Vodafone, Santo came up with a simple, direct global idea that's easy to adapt locally: Power to you. The idea is that Vodafone makes things people want possible. That message is hilariously conveyed in its first campaign, about a young man's search for Cuban-American actress Eva Mendes' phone number. He calls various people, tracks down her producer through a website and e-mail, gets her manager's name by pretending to be a director, and disguises himself in a wig and mustache to impersonate the director in a meeting with the manager, who gives him Eva's number. She answers. Of course, he panics and hangs up, but the "Power to you" message is clear.

"Santo worked with Team Vodafone from WPP [and is] a very internationally-oriented agency with a creative freshness that stood out," said David Wheldon, Vodafone's global brand director. "As nearly all executions are done locally, Santo's collaborative working skills are helping and inspiring our great local partners."

Brands from scratch
Maxi and Seba are part of a coterie of Argentine creatives who started at local shops like Agulla & Baccetti, an iconic Buenos Aires agency in the 1990s, then worked in the U.S. or Europe at Wieden & Kennedy or Mother before returning to Argentina, often when they started families. Mr. Anselmo, 40, remained at Agulla & Baccetti as chief creative officer while Mr. Wilhelm, 37, left Argentina in 2001 to work at Mother London, then Wieden & Kennedy Amsterdam. Other returnees include Juan Cabral, a Mother and Fallon veteran who is back in Buenos Aires, and Carlos Bayala, who worked at Wieden and Mother before opening Mother's Latin America outpost Madre in Buenos Aires.

Santos' founders say they share a dream: to work for the world from Argentina. Vodafone and Coca-Cola are helping to make that dream come true, along with another one -- to build brands from scratch. After numerous international assignments, Coke approached Santo last year with a sample of a new product, a mix of milk and fruit juice that the company wanted to try.

"We worked together creating a whole new brand, finding the name of the product and designing its packaging," Mr. Wilhelm said. They came up with the name Hugo for the product, and a goofy Hugo character who was supposedly behind the brand, even creating his own ads featuring testimonials from his mother and grandmother. (In fact, they were Mr. Wilhelm's mother and grandmother.)

Hugo launched first in Chile, and will roll out in Argentina and Peru. It captured a 6% share of Chile's juice market in the first month, and 10,000 fans signed up on the brand's site.

Guido Rosales, Coke's creative excellence director for Latin America, summed up the Santo formula in three words: partnership, integration and integrity. "They have this way of saying what comes to their minds spontaneously and they are brutally honest when giving their opinion. Somehow, they manage to be totally open to what we have to say at the same time."

Santo also helped local cellphone provider Personal Mobile launch an online music store for its subscribers. Santo designed the site, visual identity and ad campaign. Ads were based on the premise that everyone secretly enjoys at least one song from an artist they despise. In one popular spot, a gang of heavy metal devotees bop to a Britney Spears song, downloaded covertly from the Personal Music Store. In three months, the website sold more than 1 million downloads, and now outsells Argentina's largest music store, Musimundo.