Telecommunication networks will be based on the Internet protocol or IP in the future. As a network layer protocol the IP protocol alone is not sufficient; not even with suitable Internet transport protocols such as TCP, UDP, and RTP. In the Internet community, that is the Internet Engineering Task Force or IETF, large numbers of activities are going on to specify new protocols and application programming interfaces (APIs) to provide a complete networking solution. This paper examines the implications of all IP-networks on middleware. A special emphasis is on the interoperability of specifications defined in various standardization bodies and consortia. In particular, we discuss the danger of interpreting “all IP” as specified in the IETF since then a huge amount of work, well-established specifications and mature software products is not employed.