The developers of the two biggest consumer and corporate electronic messaging products today said they're conducting a joint interoperability test on their instant messaging systems using the Simple protocol, one of three standards under study by the IETF (Internet Engineering Task Force).

Lotus and America Online said they would test Simple (Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions) together to see whether IM systems can communicate securely.

But this is not the major move that AOL needs to make. It already allows crossover of buddies between its and Lotus' systems, whereas it is required to find a way of allowing crossover between its AIM system and competitors' systems such as Microsoft's MSN Messenger.

"The trial will involve two distinct IM test systems, AOL's AIM and Lotus Sametime. The systems will communicate with each other on a server-to-server basis via Simple," said the companies in a joint statement.

In approving AOL's merger with Time Warner, the US Federal Communications Commission required the company to open its dominant instant messing service to third-party IM services, such as Microsoft's MSN Messenger and Yahoo's Yahoo Messenger.

Simple is one of three protocols the IETF was considering as a standard for instant messaging. Earlier this year, the standards body indicated there might instead be a combined standard. That would include parts of the other two protocols, which are known as Presence and Instant Messaging (PRIM) and IMXP, which is based on block extensible exchange protocol (BXXP).