Zhone IMA CS-200 System Reference Manual page 289

Out of Service, an indication that a system element has failed.
OSI
Open Systems Interconnection
PAM
Pulse Amplitude Modulation
PBX
Private Branch Exchange, a small phone switch inside a company.
PCM
Pulse Code Modulation
PDU
Protocol Data Unit
ping
A program used to test IP-level connectivity from one IP address to another.
PLAR
Private Line Automatic Ringdown
PLR
Pulse Link Repeater
POP
Point of Presence, usually a telephone carrier office.
POTS
Plain Old Telephone Service
PPO
PPhone Foreign Exchange Office port. An interface at the end of the FX line connected to
DMS SuperNode Switch.
PPP
Glossary -15