São Paulo: As Brazil's largest city, São Paulo has excellent 4G and growing 5G coverage, particularly in central areas like Avenida Paulista and business districts. The Metrô system offers reliable signal on most station platforms and within trains, though connections can be intermittent in deeper, older tunnel sections. Indoor coverage is strong in modern shopping malls and office buildings but can be weaker inside dense, concrete residential blocks.

Rio de Janeiro: Expect strong connectivity across the famous South Zone (Zona Sul) districts like Copacabana and Ipanema, as well as the city center. Signal is generally good at the top of Sugarloaf Mountain and Christ the Redeemer, though networks can be congested. The MetrôRio provides coverage on platforms, but service can drop between stations in the underground tunnels of Lines 1 and 2.

Salvador: The main urban and coastal areas have solid 4G coverage. However, in the historic Pelourinho district, the narrow colonial streets and thick stone walls can cause the signal to be inconsistent. Salvador's Metrô system runs mostly above ground, ensuring a stable connection throughout your journey. Indoor reception is best in modern hotels and shopping centers.

Brasília: The nation's capital, with its wide-open avenues and modern design, offers outstanding mobile coverage. The planned layout minimizes signal obstruction across the city's main residential and monumental areas. The Metrô-DF also runs primarily above ground, providing continuous and dependable service while traveling between the city's "wings".

Manaus: Within the urban center of Manaus, you will find dependable 4G service perfect for navigating the city. However, it is crucial to note that mobile signal disappears rapidly once you leave the city limits for Amazon River or jungle tours. Expect to be offline during these excursions, making the eSIM ideal for your time in the city itself but not for deep-forest adventures.

Major BR Highways: Coverage is generally reliable on key federal highways in the Southeast, such as the BR-116 (Rodovia Presidente Dutra) between São Paulo and Rio de Janeiro, and the BR-101 along the southern coast. However, as these highways extend into the Northeast or Central-West regions, you will encounter long stretches with weak or no signal, particularly between smaller towns.

Vitória-Minas Railway (EFVM): As one of Brazil's few long-distance passenger train services, the EFVM route between Vitória and Belo Horizonte passes through many rural and mountainous areas. Expect intermittent connectivity and frequent signal drops for the majority of the journey outside of major station stops.

Serra do Mar & Serra da Mantiqueira: When traveling on highways that cross these major coastal mountain ranges in Southeastern Brazil, such as sections of the BR-116 or BR-040, cellular service is often unstable. Winding roads, deep valleys, and dense vegetation cause frequent signal loss until you reach lower elevations or populated areas.

Long Tunnels and Bridges: Major infrastructure like the series of tunnels on the Rodovia dos Imigrantes highway (linking São Paulo to the coast) and the Rio-Niterói Bridge can interrupt your connection. Most long road tunnels in Brazil do not have cellular repeaters, so expect a complete loss of signal until you exit.

The Amazon and Pantanal Regions: Once you venture outside of major urban centers like Manaus, Belém, or Cuiabá into the Amazon Rainforest or the Pantanal wetlands, you will lose cellular service almost immediately. These vast regions have virtually no coverage, making satellite-based devices the only reliable option for communication.