Welcome to the ZyXEL Networking Glossary - your definitive source for descriptions of networking terms and ZyXEL's product features.
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Annex I is an addendum to the ADSL2+ standard (ITU G.992.5). Also known as all digital mode, the ADSL connection uses the full spectrum of the physical line. This increases the upstream data rate. You cannot use POTS or ISDN service while using Annex I.