ISDN用户网络接口规范 第三层基本呼叫控制协议Q.931国家标准（中文）。可以做为ISDN、VOIP H.225的参考资料。-ISDN User Network Interface Specification third tier basic call control protocol Q.931/Network national standards (Chinese). ISDN can be used as a VOIP H.225 reference.

Si4421（433M无线收发模块）打包资料, 包括中文手册，中文资料，例子程序，基本电路，模块设计参数及图片。-Si4421 (433M wireless transceiver module) package of information, including the Chinese manual, the Chinese data, example programs, basic circuit module design parameters and photo.