Instant messaging is hardly a new concept -- even for mobile phone users -- but enabling users to send and receive more IMs is the talk of the town at the 3GSM World Congress in Barcelona.

Fifteen GSM operators unveiled plans at 3GSM to cooperate to ensure that users can send instant messages across different global networks.

Meanwhile, Microsoft Corp. (Nasdaq: MSFT) -- one of the big names in consumer and enterprise desktop IM -- has just announced its Office Communicator Mobile client, which promises secure IM for enterprise users on handhelds, smartphones, and other devices.

The GSM operators, which include huge names such as China Mobile Communications Corp. , Orange SA , Telefónica Móviles SA , Telecom Italia Mobile SpA (Milan: TIM), T-Mobile International AG , and Vodafone Group plc (NYSE: VOD), will sign bilateral interoperability agreements to enable transfers of instant messages across their networks.

The idea, according to the GSM Association (GSMA) , is to make IMs as easy to use on mobile phones as the wildly popular SMS text messaging system already is. In China alone, 306.4 billion SMS messages were sent in 2005, according to the Xinhua news agency.

Many users already have a mobile IM client on their phone, usually a cutdown version of a desktop client, such as AOL Instant Messanger or MSN Messenger. Like the desktop clients, however, there is currently little or no interoperability between the messaging software. As it stands, SMS is the only consistent way to text message users on other operators' networks.

While such an agreement might obviate many of these issues, American carriers may once again be late to the interoperability party. One operator conspiciously absent is Cingular Wireless , the largest GSM operator in the U.S.

Cingular hasn't yet replied to calls to ask if it will get involved later.

Microsoft, meanwhile, is promising sophistication rather than interoperability for its new corporate mobile IM client. The product, called Microsoft Office Communicator Mobile, runs on the Microsoft Office Live Communications Server 2005.

The software giant says that the mobile client also offers integrated VOIP services and "presence" features that let people see whether a user is online, on the phone, or out of the office, as well as remote access to enterprise resources from WiFi hotspots and corporate networks.

— Dan Jones, Site Editor, Unstrung