You have just obtained a modular Cisco router with 2 serial connections and a BRI/U interface.What other physical piece of hardware is required in order to establish an ISDN connection?是什么意思_You have just obtained a modular Cisco router with 2 serial connections and a BRI/U interface.What other physical piece of hardware is required in order to establish an ISDN connection?在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句