Since then , both IBM Lotus and Microsoft have introduced federation between their EIM systems and some of the public IM networks thus employees may use a single interface to both their internal EIM system and their buddies on AOL , MSN , and Yahoo ! . Both IBM Lotus and Microsoft have introduced federation between their EIM systems and some of the public IM networks so that employees may use a single interface to both their internal EIM system and their contacts on AOL , MSN , and Yahoo ! .