Technically yes but I hear it most often referred to as 4ESS/5ESS, then custom, then NI1.
A more technical representation would be:
1-a AT&T TR 41449/ 41459
1-b Bellcore TR 1268;
NIUF.302; ANSI T1.607
1-c NORTEL DMS-250 BCS36/IEC01 Service
1-d Telecordia SR-4287 Service
-CL