[计] frequency division switching system
pín fēn zhì jiāo huàn jī xì tǒng ㄆㄧㄣˊ ㄈㄣ ㄓˋ ㄐㄧㄠ ㄏㄨㄢˋ ㄐㄧ ㄒㄧˋ ㄊㄨㄥˇ