SMSGupShup, a Twitter-like service in India, is getting a ton of buzz over here in the U.S., too. In an interview with CEO Beerud Sheth now says the service now has 20 million users (and that’s without an appearance on Oprah), nearly all of which are in India. That’s up from 7 million late last year.The service can only be accessed via SMS, which works just fine for India’s 400 million mobile phone users (there are just 40 million broadband Internet users, Sheth says). Users sign up and use the service all via text messages. They never need to visit the website at all.The service’s main variable costs are fees for text messages, and Sheth says that they’ve had to implement caps to keep costs under control. But as the service grows, says Sheth, they are able to negotiate much better pricing. Already SMSGupShup accounts for 400 million monthly text messages, around “5%-6%” of the total Indian market.Three months ago the service added advertising to messages. Three months in and they’re making $150,000/month in revenue. Not bad for a SMS-based service.The full video interview is below. Thanks to Robert Scoble who participated briefly in the interview. Crunch Network: CrunchGear drool over the sexiest new gadgets and hardware.