企业通信网络是指在企业内部建立的通信网络，用于实现企业内部的通信和协作。QSIG和H.323是两种常用的企业通信网络协议，它们分别用于传输语音和数据。在企业通信网络中，呼叫转移是一项非常重要的功能，它可以将来电转移到其他电话或者语音信箱中，以便用户能够及时处理来电。

ISO/IEC 21411:2001标准规定了QSIG和H.323之间的信令交换，以实现呼叫转移功能。该标准定义了QSIG和H.323之间的信令互通机制，包括呼叫转移请求、呼叫转移确认、呼叫转移拒绝等信令。同时，该标准还规定了QSIG和H.323之间的信令传输协议，包括信令传输的格式、编码和解码方式等。

该标准的实现可以使企业通信网络中的QSIG和H.323之间实现呼叫转移功能，提高了企业通信网络的可靠性和灵活性。同时，该标准的实现还可以促进不同厂商的企业通信网络之间的互通，降低企业通信网络的成本和维护难度。

相关标准
- ISO/IEC 11579-1:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call transfer supplementary service -- Part 1: Protocol specification
- ISO/IEC 11579-2:1995 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call transfer supplementary service -- Part 2: Protocol implementation conformance statement (PICS) proforma
- ISO/IEC 13870:1998 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call transfer supplementary service using DSS1 protocol
- ISO/IEC 13871:1998 Information technology -- Telecommunications and information exchange between systems -- Private Integrated Services Network -- Inter-exchange signalling protocol -- Call transfer supplementary service using QSIG protocol
- ISO/IEC 14772-2:1999 Information technology -- Computer graphics and image processing -- Virtual reality modelling language -- Part 2: Interactive 3D graphics