TETRA is one of the most widely used standards in trunking communications. GSM-R is the special communication technology for railway based on GSM.是什么意思_TETRA is one of the most widely used standards in trunking communications. GSM-R is the special communication technology for railway based on GSM.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句