Moroni: As the capital on Grande Comore, Moroni offers the most reliable 4G coverage, especially in the city center, around the Volo Volo Market, and key government areas. Connectivity is strong for general use, but signal can weaken inside older buildings constructed with thick volcanic stone. As you travel away from the city towards the slopes of Mount Karthala or remote coastal areas, expect the network to drop to a less consistent 3G signal.

Mutsamudu: The main port city on Anjouan has dependable 4G service in its commercial center and around the bustling harbour. The island's steep, hilly terrain means that mobile signal can become patchy quickly once you leave the dense urban core. In the historic medina, the narrow alleyways and old stone buildings can sometimes interfere with indoor reception, making it weaker than out on the main streets.

Fomboni: On the less-developed island of Mohéli, Fomboni provides stable 3G and some pockets of 4G service concentrated in the main town, suitable for messaging and basic browsing. Coverage diminishes significantly outside the town limits. Tourists visiting the Mohéli Marine Park or exploring the island's forested interior should be prepared for very limited or non-existent mobile signal.

Domoni: This historic town on Anjouan features good 3G and basic 4G connectivity within its main populated areas. Service is generally reliable for calls and data along the coastal road and in the town itself. However, the surrounding mountainous landscape can create signal dead spots, and frequent power fluctuations on the island can occasionally affect network stability.

Coastal Ring Roads: Mobile signal is generally reliable along the main paved roads circling each island, such as the routes connecting Moroni with other towns on Grande Comore or Mutsamudu with Domoni on Anjouan. Expect intermittent signal drops and a switch to slower networks in more remote coastal stretches between major settlements.

Mountainous Interior: Connectivity deteriorates significantly when traveling away from the coast. The forested slopes of Mount Karthala on Grande Comore and the rugged central highlands of Anjouan have very limited to non-existent cellular coverage. Plan to be offline when hiking or driving through these interior regions.

Inter-Island Ferries: When traveling by ferry between Grande Comore, Anjouan, and Mohéli, your cellular signal will be lost shortly after departing the port. The majority of the sea journey is out of range of land-based towers, with service only returning as you approach the destination island.

Mohéli Island: On the island of Mohéli, which is also a national park, consistent coverage is largely confined to the main town of Fomboni. Outside of Fomboni and along the primary coastal road, service becomes extremely sparse or unavailable, particularly in the southern and western parts of the island.