Bubbly, a service that allows users to send voice messages to multiple followers, has gained 500,000 users in India in the first four weeks of launch.

The number blasted expectations out of the water, said Tom Clayton, chief executive of Bubble Motion, the Sequoia Capital-backed startup that created the Bubbly service.

“We were expecting 10,000 to 20,000 users in the first couple months,” Clayton said. “We haven’t even really told anyone about it, it’s just sort of grown virally.”

Bubbly is cell phone service that aims to bring social media to the masses. It builds on the foundation set by Bubble Talk, which has 100 million users who use the service to send voice messages to on other individuals. With Bubbly, messages go to a bigger audience — followers.

Users can easily follow friends, family, celebrities, religious leaders, and BBC News by typing in the person’s number or access code, then *. They’re notified when there’s an update –- a friend inviting a group of classmates to a bar, a short news update from BBC News, or a message for fans from a Bollywood star.

Followers get notified when someone sends out a new voice message – normally just 30 seconds long -– and Bubble Motion earns money by taking a cut of the airtime used to listen to the message. It’s free to send a message, though in the case of celebrities, it could be thousands of fans who dial in.

“From a fan’s perspective, there’s a little more intimacy from hearing the voice,” Clayton said. “They know it’s not fake or a PR agent or some guy in a call center typing out a message.”

Most of the 500,000 new users are teens and tweens, Clayton said. The average Bubbly message gets listened to by about half of the senders’ followers. The company has launched the service in three of India’s 23 cell phone service areas, and plans to expand to the rest of India, Japan, Europe the Middle East and later, Brazil.

Bubble Motion also hopes to offer video Bubbly messages, where followers could easily dial into watch homemade videos, or even give users the option of including text – making it a true mobile Twitter.

There’s just one glitch to that idea, though -– Bubble Motion wouldn’t make money off texting, because users in Asia don’t pay to receive text messages.