Facebook and Twitter are surely be the most popular and most influential social networks on the Internet. But Indian SMS-based social network GupShup’s 26 million members proves that sites not built and hosted from the San Francisco Bay Area can attract large audiences.

GupShup published a press release this morning claiming a user base of 26 million people, adding the claim that this makes it India’s largest social network:

Part of SMS GupShup’s success has been the penetration of mobile phones in India. India’s social networking is taking off on mobile as the country currently has about a 10-1 mobile to PC ratio with SMS serving as the most pervasive communication platform. SMS GupShup is currently processing over 480 million messages a month and accounts for an astounding 5% of all texts sent within India.

The community has attracted a broad base of audiences ranging from sports fans to religious groups to commuters interested in up to the minute traffic alerts.  Currently over 2 million groups exist on the community with the average SMSGupShup member belonging to 2.75 groups. A list of premier groups can be found here: http://www.smsgupshup.com/communities.

Outside the U.S., SMS offers billions of potential customers a cheap way to commicate compared to the Internet-based data plans of AT&T and Verizon. Given the economics, it’s not a big surprise that a large number of Indian phone users would opt for cheap SMS-based GupShup rather than Facebook. And while Twitter itself was designed as an SMS service — hence its 140 character limit on tweets, based on the 160-character limit of SMS messages — GupShup offers users in India a local service built upon relatively cheap SMS rather than Internet data.

GupShup comes from startup company Webaroo, which has offices in both Cupertino and Mumbai. So far, the company has raised $22 million and change from reputable investors including Charles River Ventures.