Polycom ViewStation FX

Appendix D PRI Technical Notes
© Polycom, Inc. 193 ViewStation FX/VS 4000 User’s Guide
Glossary of Terms
The following defines terms related to PRI T1 and E1.
B7ZS
A method of signal encoding used with T1. This method is no longer
widely deployed.
B8ZS
A method of signal encoding used with T1.
CPE
Customer Premise Equipment. Network endpoint equipment that is
used at a customer site.
CRC
Cyclic Redundancy Check. An error-detection mechanism.
CRC4
A CRC algorithm used with E1.
CSU
Channel Service Unit. A device that isolates CPE from the network.
Used in North America only.
Downstream
Away from the network and towards the Customer Premise
Equipment.
E1
A 2.048 Mbps carrier that supplies 30 data channels at 64 kbps and
one signaling channel.