| Annex J | |
| Status: | In force |
| Organization: | ITU-T |
| Base Standards: | G.992.3 |
| Domain: | telecommunications |
| License: | Freely available |
| Website: | https://www.itu.int/rec/T-REC-G.992.3/ |
Annex J is a specification in ITU-T Recommendations G.992.3 and G.992.5 for all digital mode ADSL with improved spectral compatibility with ADSL over ISDN, which means that it is a type of naked DSL which will not disturb existing Annex B ADSL services in the same cable binder.[1] [2]
This specification has the same upstream/downstream frequency split of 276 kHz as Annex B, but does not have lower frequency limit of 138 kHz, allowing upstream bandwidth to be increased from 1.8 Mbit/s to 3.5 Mbit/s. This is similar to Annex M, but Annex J can not have POTS on the same line.
Deutsche Telekom started deploying Annex J in 2011, Vodafone Germany followed suit in April 2015 (marketed as quality improvements).