说明：  SIMCOM公司的SIM300的AT指令中文版根据V.25TER的AT指令概要（Overview of AT Commands According to V.25TER） A/ 重新发送最后给的AT指令（Reissues the last command given）
(SIMCOM the company' s SIM300 Chinese version of the AT command of AT commands according to V.25TER Summary (Overview of AT Commands According to V.25TER) A/re-send the final to the AT command (Reissues the last command given))