Annex J is a specification in ITU-T Recommendations G.992.3 and

G.992.5 G.992.5 (also referred to as ADSL2+, G.dmt.bis+, and G.adslplus) is an ITU-T standard for asymmetric digital subscriber line (ADSL) broadband Internet access. The standard has a maximum theoretical downstream sync speed of 24 Mbit/s, megabits per ...

for all digital mode ADSL with improved spectral compatibility with ADSL over

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work ...

, which means that it is a type of

naked DSL A naked DSL, also known as standalone or dry loop DSL, is a digital subscriber line (DSL) without a PSTN ( analogue telephony) service — or the associated dial tone. In other words, only a standalone DSL Internet service is provided on ...

which will not disturb existing Annex B ADSL services in the same cable binder. 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 In telecommunications, data-transfer rate is the average number of bits ( bitrate), characters or symbols ( baudrate), or data blocks per unit time passing through a communication link in a data-transmission system. Common data rate units are mu ...

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 Vodafone Group plc () is a British multinational telecommunications company. Its registered office and global headquarters are in Newbury, Berkshire, England. It predominantly operates services in Asia, Africa, Europe, and Oceania. , Vod ...

Germany followed suit in April 2015 (marketed as quality improvements). ADSL annex overview

External links

ITU-T Recommendation G.992.3: Asymmetric digital subscriber line transceivers 2 (ADSL2)ITU-T Recommendation G.992.5: Asymmetric Digital SubscriberLine (ADSL) transceivers - Extended bandwidth ADSL2 (ADSL2+)

References

ITU-T recommendations ITU-T G Series Recommendations Digital subscriber line G.992.2_Annex_J Telecommunications-related introductions in 2002 {{telecomm-stub