APS and 4ESS software, but replaces the 1B processor and the peripheral units which run in emulated environments on an ATCA blade or commercial off-the-shelf servers. The N4E-N1B is based on the Alcatel-Lucent (now Nokia) gateway platform (7520 Media Gateway (MGW)), 1310 Operations and Management Console – Plus (OMC-P) and the 5400 Linux Control Platform (LCP) and includes other elements such as MRV console terminal servers. Starting in the late 2010s and continuing in the early 2020s, AT&T is replacing older 4ESS switches with N4E-N1B switches, and is also adding new N4E-N1B switches in places where there was no 4ESS previously. It is assumed that these new N4E-N1B switches are taking over Class-4 functions that were previously handled by 5ESS switches acting as "edge tandems." See also 1ESS switch 5ESS switch Telephone exchange Bell System Practices References External links Bell System commercial about the 4ESS switch on YouTube https://telephoneworld.org/telephone-switching-systems/western-electric-lucent-modern-telephone-switching-systems/ https://telephoneworld.org/landline-telephone-history/the-crash-of-the-att-network-in-1990/ AT&T 4ESS Tandem crash of 1990 Telephone exchange equipment