AT指令完全手册，详细介绍了各种AT指令格式及其功能，包括基本的连接AT指令及其语音和传真AT指令。对于modem开发是必须的文档。-AT command completely manual, detailing the various AT command format and function, including basic connectivity AT commands, and their voice and fax AT command. For modem development is necessary documents.