Editing ISDN (section)

=== Germany ===
[[File:DBP 1988 1368 ISDN.jpg|thumb|German stamp]]

In [[Germany]], ISDN was very popular with an installed base of 25 million channels (29% of all subscriber lines in Germany as of 2003 and 20% of all ISDN channels worldwide). Due to the success of ISDN, the number of installed analog lines was decreasing. [[Deutsche Telekom]] (DTAG) offered both BRI and PRI. Competing phone companies often offered ISDN only and no analog lines. However, these operators generally offered free hardware that also allows the use of POTS equipment, such as NTBAs ("[[:de:Network Termination for ISDN Basic rate Access|Network Termination for ISDN Basic rate Access]]": small devices that bridge the two-wire UK0 line to the four-wire S0 bus) with integrated [[terminal adapter]]s. Because of the widespread availability of ADSL services, ISDN was primarily used for voice and fax traffic.

Until 2007 ISDN (BRI) and [[ADSL]]/[[VDSL]] were often bundled on the same line, mainly because the combination of DSL with an analog line had no cost advantage over a combined ISDN-DSL line. This practice turned into an issue for the operators when vendors of ISDN technology stopped manufacturing it and spare parts became hard to come by. Since then phone companies started introducing cheaper xDSL-only products using [[VoIP]] for telephony,<ref>{{cite web|last1=Neuhetzki|first1=Thorsten|title=Arcor will ab Sommer Fernsehen per Internet anbieten|url=http://www.teltarif.de/arch/2007/kw04/s24629.html|website=teltarif.de|access-date=7 May 2016|date=24 Jan 2007|quote=Arcor setzt im Endkundenbereich auf NGN|archive-date=2 June 2016|archive-url=https://web.archive.org/web/20160602023102/http://www.teltarif.de/arch/2007/kw04/s24629.html|url-status=live}}</ref> also in an effort to reduce their costs by operating separate data & voice networks.

Since approximately 2010, most German operators have offered more and more VoIP on top of DSL lines and ceased offering ISDN lines. New ISDN lines have been no longer available in Germany since 2018, existing ISDN lines were phased out from 2016 onwards and existing customers were encouraged to move to DSL-based VoIP products.
Deutsche Telekom intended to phase-out by 2018<ref>{{cite web|last1=Niek Jan van Damme|title=Deutsche Telekom - 100% IP by 2018|website=[[YouTube]] |url=https://www.youtube.com/watch?v=3JNSTrNFgCM| archive-url=https://ghostarchive.org/varchive/youtube/20211211/3JNSTrNFgCM| archive-date=2021-12-11 | url-status=live|access-date=7 May 2016|date=16 March 2014}}{{cbignore}}</ref> but announced the complete transition in 2020,<ref>{{Cite web |last=AG |first=Deutsche Telekom |date=2020-03-02 |title=Five facts about the IP migration |url=https://www.telekom.com/en/company/details/five-facts-about-the-ip-migration-596110 |access-date=2025-04-13 |website=www.telekom.com |language=en}}</ref> other providers like Vodafone estimate to have their phase-out completed by 2022.