Abstract: The invention relates to an address conversion process for porting a telecommunications application APP from the TCP/IP network to the OSI/CO network, and to an address conversion module used in this process. In a known manner, access to the networks is authorized by way of a "socket" interface (SOC) for the TCP/IP network, and an "XTI" interface for the OSI/CO network. In a notable manner, the "socket" interface calls (SC), like a plurality of system cells (SY), are in a first time period oriented, at the moment of the link editing phase prior to obtaining the executable, to a module (W) for automatic address conversion of the library type. This module (W) then performs the conversion of the addresses specific to the TCP/IP network into addresses of the OSI/CO network and enables the passage from the TCP/IP protocol to the OSI/CO protocol. After conversion, the calls are transmitted to the "XTI" interface and can be used directly in the OSI/CO network.