IBM and Siemens Enterprise Communications have had a strong relationship going back many years when the computer giant sold its Rolm operations to Siemens. IBM also has a strong relationship with Nortel extending to providing server equipment for a variety of Nortel telephony systems for both small and large business customers. Other enterprise communications system suppliers also work with IBM in support of Lotus Sametime integration with their IP telephony systems, and Avaya is one of many telephony system suppliers who support Microsoft's OCS solution for unified communications applications. It is important that IBM work with a market leader such as Avaya as a strategic initiative to compete against Microsoft, but the relationship also benefits Avaya in a similar way. There is little doubt that Microsoft is intent on making a big splash in the telephony market and pushing aside the traditional PBX system suppliers with its fully integrated telephony/unified communications OCS offering.