As a complementary service, messaging promises to be a major competitive battleground going forward. That's why Microsoft (NASDAQ:MSFT) acquired Skype for $8.5 billion. Google (NASDAQ:GOOGL) may be about to unify its messaging services, Apple (NASDAQ:AAPL) has iMessage and FaceTime, while Facebook (NASDAQ:FB) is also beefing up its mobile messaging prowess.

One of the smaller up-and-comers is Viber, which offers a cross-platform messaging service that includes free video calling. Viber just announced that it was launching a desktop client, which will compete directly with Skype. At the same time, Viber disclosed that it's now up to 200 million active users, compared to the 300 million that Skype currently has.

In the video below, Fool contributor Evan Niu, CFA, discusses the mobile messaging landscape and why Microsoft may be safe for a little while.