Editing Synchronous optical networking (section)

==End of life and retirement==
SONET/SDH was used by [[internet access provider]]s for large customers, and is no longer competitive in the supply of private circuits. Development has stagnated for the last decade (2020) and both suppliers of equipment and operators of SONET/SDH networks are migrating to other technologies such as OTN and wide area Ethernet.

British Telecom has recently (March 2020) closed down their KiloStream and Mega Stream products which were the last large scale uses of the BT SDH. BT has also ceased new connections to their SDH network which indicates withdrawal of services soon.<ref>[https://www.ofcom.org.uk/__data/assets/pdf_file/0018/63225/final-statement.pdf KiloStream Retirement]</ref><ref>[https://www.packetlight.com/products/wdm-products-by-category/otn-layer SDH to OTN Migration]</ref><ref>{{Cite web |url=http://www.ftiltd.co.uk/communication/ |title=MegaStream Withdrawal |access-date=4 July 2020 |archive-date=5 July 2020 |archive-url=https://web.archive.org/web/20200705022230/http://www.ftiltd.co.uk/communication/ |url-status=dead }}</ref>