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 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. ...

, which means that it is a type of naked DSL 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 The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base uni ...

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 multi ...

to 3.5 Mbit/s. This is similar to Annex M, but Annex J can not have POTS on the same line.

Deutsche Telekom Deutsche Telekom AG (, ; often just Telekom, DTAG or DT; stylised as ·T·) is a partially state-owned German telecommunications company headquartered in Bonn and the largest telecommunications provider in Europe by revenue. It was formed in 199 ...

started deploying Annex J in 2011,

Vodafone Vodafone Group Public Limited Company () is a British Multinational company, multinational telecommunications company. Its registered office and global headquarters are in Newbury, Berkshire, England. It predominantly operates Service (economic ...

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 Telecommunications-related introductions in 2002 {{telecomm-stub