| Abbreviation | Definition |
|---|---|
| LIDB | Line Information DataBase |
| LIU | Line Interface Unit |
| LLB | Line LoopBack |
| LLC | Local Leased Circuit |
| LLU | Local Loop Unbundling |
| LMC | Loop Maintenance Center |
| LME | Line Monitoring Equipment |
| LMI | A Local Managed Internetworks |
| LMOS | Loop Maintenance Operations System |
| LMS | Local Measured Service |
| LMSR | Last Mile Subscriber Return |
| LMU | Line Monitor Unit |
| LND | Last Number Dialed |
| LOF | Loss Of Frame |
| LOH | Line OverHead |
| LOP | Loss Of Pointer |
| LOP-L | Loss Of Pointer - Line |
| LOP-P | Loss Of Pointer - Path |
| LOP-V | Loss Of Pointer - Virtual |
| LOS | Levels Of Service |