ðeɪ tˈɪpɪkli kənsˈɪst ʌv pɹəpɹˈaɪətɛɹi hˈɑːɹdwɛɹ wˌɪtʃ ɪz ɐtˈætʃt tə ðə tɹˈʌŋk lˈaɪnz fɚðɪ ˈɛntɚpɹˌaɪz tˈɪpɪkli pˈɑːts, tˈiː wˈʌn, ɔːɹ ˈiː wˈʌn lˈaɪnz.
They typically consist of proprietary hardware which is attached to the trunk lines for the enterprise (typically POTS, T1, or E1 lines).