ˌɛksˈoʊ kəmjˌuːnɪkˈeɪʃənz, ˌɛlˌɛlsˈiː pɹˈiːviəsli nˈɛkstlɪŋk kəmjˌuːnɪkˈeɪʃənz, kənsˈɛntɹɪk nˈɛtwɜːk kˌɔːɹpɚɹˈeɪʃən ænd ɐlˈiːdʒəns tˈɛlᵻkˌɑːm, ˈɪŋk.wʌz ɐn ɐmˈɛɹɪkən tˌɛlᵻkəmjˌuːnɪkˈeɪʃənz kˈʌmpəni.
XO Communications, LLC (previously Nextlink Communications, Concentric Network Corporation and Allegiance Telecom, Inc.) was an American telecommunications company.