This revision of ETS 300 325 shall provide bit compatibility with Common-ISDN-API v2.0 and ETS 300 325. It shall allow further common enhancements without loosing compatibility with Common-ISDN-API v2.0. This PCI shall ensure support to both application interfaces. Remarks: (agreed at TA21) The proposed scope is technically feasible. It results in offering two interface accesses (ETS 300 325 and Common-ISDN-API v2.0). The interfaces can be offered in a way, which guarantees binary compatibility to applications conforming to either specification. The code between the interface and the hardware, may or may not be common to both interface accesses. The code for the interface accesses shall comply with the definitions made for each interface, independant of whether the code is common or only able to drive one of the interface specifications. Future enhancements can be performed in a way, which does not destroy this binary compatibility. Consequently, this revision of ETS 300 325 shall maintain both descriptions (ETS 300 325 and Common-ISDN-API v2.0) besides a part, which contains common aspects and overall features. With this development future implementations will ensure cross compatibility between both specifications. ETS 300 325 is also to be revised to include 3 groups of extensions: -New exchange mechanism (Windows NT, OS2, Netware) -New user protocols (PPP, SDLC, VMO, inverted MDLC, PCM 56 kbit/s) -Miscellaneous features (DTMF, parameter duplication, extension messages)