本文介紹了一種基于公共電話網（PSTN）的電梯安全呼叫系統(tǒng)，采用總線拓撲結構
和DTMF 信號對電梯群進行組網，構成由電梯分機、機房電話和小區(qū)管理中心的管理主機組成的小區(qū)電梯安全呼叫網絡，并通過管理主機實現與公共電話網通信。本文重點講述了管理主機部分的軟件設計。
關鍵字：公共電話網 雙音多頻 電梯呼叫系統(tǒng) uC/OS-II

Abstract: The article designs a kind of elevator call system based on PSTN. This system
organizes elevator group as a network, and makes up of the community elevator call system which is constituted by elevator extension、central room telephone and the community’s manage host phone by adopting the bus topology and using DTMF as the system’s signal. The system can communicate with the public switching telephone network through the community’s manage host phone. The article mainly introduces the software design of the community’s manage host phone.
Keywords: PSTN DTMF Elevator Call System uC/OS-II