| Abbreviation | Definition |
|---|---|
| ODCH | Oracle Direct Connector for HDFS |
| ODCM | On Demand Clock Modulation |
| ODCP | Onboard Digital Control Processing |
| ODCV | On Device Cardholder Verification |
| ODL | Optical Data Link |
| ODTA | Open Distributed Telecommunication Architecture |
| ODU | Outdoor Unit |
| OE | Originating Equipment |
| OFA | Optical Fiber Amplifier |
| OFE | Owner-Furnished Equipment |
| OFN | Optical Fiber Non-conductive |
| OGX | Out-Going eXchange |
| OH | Off Hook |
| OHP | On-Hold Player |
| OICK | Originating IN Category Key |
| OIL | Outstanding Incidents List |
| OIM | Operations Interface Module |
| OITD | Over-Issued Telephone Directories |
| OLEC | Other Local Exchange Carrier |
| OLNS | Originating Line Number Screening |