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Exhibit 21 Subsidiaries of the Registrant Organizedunder the laws ofAlteon WebSystems, Inc.
    
    State of DelawareAlteon WebSystems AB
    
    SwedenAlteon WebSystems International Limited
    
    BermudaAlteon WebSystems International, Inc.
    
    State of DelawareArchitel Systems Corporation
    
    CanadaArchitel Systems (U.S.) Corporation
    
    State of DelawareArchitel Systems (UK) Limited
    
    United KingdomCoreTek, Inc.
    
    State of DelawareNortel Networks Applications Management Solutions Inc.
    
    State of DelawareNortel Networks HPOCS (Denmark) Holding A/S
    
    Denmark (Copenhagen)Nortel Networks HPOCS (Denmark) Holding Aps
    
    Denmark (Copenhagen)Nortel Networks Limited
    
    Canada1328556 Ontario Inc.
    
    OntarioCapital Telecommunications Funding Corporation
    
    CanadaCTFC Canada Inc. (formerly Colombia Telecommunications Funding Corporation)
    
    CanadaNortel Networks (Asia) Limited
    
    Hong KongeASPNet Taiwan Inc.
    
    Taiwan, Republic of ChinaNortel Networks (China) Limited
    
    Republic of ChinaNortel Networks Telecommunications Equipment (Shanghai) Co., Ltd.
    
    Republic of ChinaNortel Networks (Luxembourg) S.A.
    
    LuxembourgNortel Networks International Finance & Holding B.V.
    
    The NetherlandsBrightspeed SAS
    
    FranceNortel Finance France SAS
    
    FranceNortel Communications Holdings (1997) Limited
    
    IsraelNortel Networks Communications (Israel) Limited
    
    IsraelNortel Networks (Austria) GmbH
    
    AustriaNortel Networks (Scandinavia) AS
    
    Oslo, NorwayNortel Networks AB
    
    SwedenNortel Networks Oy
    
    FinlandNortel Networks AG
    
    SwitzerlandNortel Networks BV
    
    The NetherlandsNortel Networks Engineering Service Kft.
    
    HungaryNortel Networks France SAS (f/k/a Matra Nortel Communications S.A.S.)
    
    FranceMatra Communication Cellular Terminals GmbH
    
    GermanyNortel Networks GmbH
    
    GermanyNortel Networks Germany GmbH & Co. KG
    
    GermanyNortel Networks Germany Verwaltungs-GmbH
    
    GermanyNortel Networks Hellas EPE
    
    Athens, GreeceNortel Networks Hispania, S.A.
    
    SpainNortel Networks Malta Limited
    
    MaltaNortel Networks N.V.
    
    BelgiumNortel Networks Netas Telekomunikasyon A.S.
    
    TurkeyRON  Telecom
    
    RussiaVESNET
    
    KazakhstanNortel Networks O.O.O.
    
    RussiaNortel Networks Polska Sp. z o.o.
    
    PolandNortel Networks Romania Srl
    
    Romania




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Organizedunder the laws ofNortel Networks S.A. (French entity, f/k/a Nortel Matra Cellular SCA)
    
    FranceNortel Telecom France S.A.
    
    FranceNortel Networks S.p.A.
    
    ItalyNortel Networks S.R.O.
    
    Czech RepublicNortel Networks Singapore Pte Ltd.
    
    SingaporeNortel Networks Slovensko, s.r.o.
    
    Slovak RepublicNortel Networks South Africa (Proprietary) Limited
    
    South AfricaNorthern Telecom (Portugal) S.A.
    
    PortugalNortel Networks (Thailand) Ltd.
    
    ThailandNortel Networks AS
    
    NorwayNortel Networks Chile S.A.
    
    ChileNortel Networks de Argentina S.A.
    
    ArgentinaNortel Networks de Colombia S.A.
    
    ColombiaNortel Networks de Mexico S.A. de C.V.
    
    MexicoNortel Networks de Panama S.A.
    
    Republic of PanamaNortel Networks de Venezuela Compania Anonima
    
    VenezuelaNortel Networks del Ecuador S.A.
    
    Republic of EcuadorNortel Networks del Uruguay S.A.
    
    UruguayNortel Networks Global Corporation
    
    CanadaNortel Networks Inc.
    
    State of DelawareMilcom Technologies, LLC
    
    State of DelawareNortel Networks (CALA) Inc.
    
    State of FloridaNortel Comunicaciones de Colombia S.A.
    
    ColombiaNortel Networks Capital Corporation
    
    State of DelawareNortel Networks India International Inc.
    
    State of DelawareNortel Networks International Inc.
    
    State of DelawareNortel Networks Japan
    
    JapanNortel Networks Optical Components Inc. (f/k/a Nortel Networks HPOCS Inc.)
    
    State of DelawareNortel Networks HPOCS Inc. (f/k/a Nortel Networks Optical Components Inc.)
    
    State of DelawareNortel Networks Southeast Asia Pte Ltd.
    
    SingaporeNortel Networks Technology (Thailand) Ltd.
    
    ThailandNortel Networks Technology Ltd.
    
    Cayman IslandsNortel Networks (Shannon) Limited
    
    IrelandNortel Networks Europe Sales Limited
    
    IrelandNortel Networks U.S. Finance Inc.
    
    State of DelawareNortel Networks Finance LLC
    
    State of DelawareNorthern Telecom International Inc.
    
    State of DelawareSigniant Corporation
    
    OntarioSun Healthcare Group, Inc.
    
    State of DelawareNortel Networks International Corporation
    
    CanadaNortel Telecommunications S.A.
    
    ColombiaNorthern
Telecom Comunicaciones de Colombia S.A.
    
    ColombiaNortel Networks Korea Limited
    
    KoreaNortel Networks Malaysia Sdn. Bhd.
    
    MalaysiaNortel Networks Mauritius Ltd.
    
    MauritiusNortel Networks (India) Private Limited
    
    New Delhi, IndiaNortel Networks New Zealand Limited
    
    New ZealandNortel Networks Peru S.A.C.
    
    PeruNortel Networks Technology Corporation
    
    Province of Nova ScotiaNortel Networks Telecomunicacoes do Brasil Comercio e Servicos Ltda.
    
    BrazilNortel Networks Telecomunicacoes do Brasil Industria e Comercio Ltda.
    
    State of Sao PaoloNortel Networks Telecomunicacoes Servicos e Participacoes Ltda.
    
    BrazilNortel Networks UK Limited (f/k/a Nortel Networks plc)
    
    United KingdomNortel Networks Employee Benefit Trustee Company Limited
    
    United KingdomPeriphonics Limited
    
    United KingdomPT Nortel Networks Indonesia
    
    Indonesia




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Organizedunder the laws ofRegional Telecommunications Funding Corporation
    
    CanadaTSFC Canada Inc. (formally Telecommunications Systems Funding Corporation)
    
    CanadaSonoma Systems
    
    State of CaliforniaXros, Inc.
    
    State of Delaware