According to this statement KPN will stop traditional telephony in 2010.
Microsoft is integrating Microsoft Exchange Server 2007 Unified Messaging (UM) with your company's telephony network. This is one of the most significant deployment challenges when you are deploying Unified Messaging. Interoperating with Exchange 2007 Unified Messaging will depend on your specific Private Branch eXchange (PBX) or IP/PBX configurations and may also require that you install IP/VoIP gateways, purchase additional PBX hardware, or configure and enable features on your PBXs or IP/PBXs. In some cases, the PBX may cause reduced functionality or limitations in the Unified Messaging features. This is especially true for IP/PBXs. This topic discusses the manufacturers and specific models of IP/VoIP gateways that you can configure to support Microsoft Exchange 2007 Unified Messaging (UM).