A host of fast-growing mobile messaging services are taking a big bite out of phone carriers' text-messaging revenues -- as well as old-school communication platforms such as email.

  • just. me: Launched this month by former TechCrunch CEO Keith Teare and funded by Google's investment arm.

  • KakaoTalk: Based in Korea, it makes money from advertising and promoting mobile games.

  • Kik: Canadian company's app is popular with teens but has been criticized by parents concerned that it lets users message anonymously.

  • Line: Especially popular in Japan, it offers cartoonlike characters along with games and the ability to "follow" celebrities.

  • MessageMe: Launched this year, it has drawn notice for features that let users create and send artistic "doodles" to their friends.

  • Pinger: San Jose company offers ad-supported free texting and phone calls.

  • SnapChat: A photo-sharing app whose images self-destruct, leading many to label it "the seating app."

  • Tango: Lets users send text messages and play games but also offers free voice and video calling.

  • TicToc: Another Korea-based messaging service that offers unlimited calls and messages and group chat.

  • Viber: Claims 175 million users; recently signed a deal with an Indonesian telecom carrier to be its preferred messaging app.

  • WeChat: With more than 300 million users, it's owned by the Chinese Internet conglomerate Tencent.

  • WhatsApp: Fast-growing but low-profile San Francisco startup claims its user base now outstrips Twitter's.