Figure 2-6. Connecting A Pri Isdn Network Interface - Bay Networks 5393 Hardware Installation Manual

When the connector clicks into place, the connection is secure.
Appendix A describes the PRI ISDN Network Interface port's
signal/pin allocation.
For T1 applications, the 5393 Remote Annex/PRI utilizes an
internal Channel Service Unit (CSU). An internal CSU is not
used in E1 applications.

Figure 2-6. Connecting a PRI ISDN Network Interface

Remote Annex 5393/PRI Hardware Installation Guide
Chapter 2 Installing the Remote Annex 5393/PRI
2-13