| Abbreviation | Definition |
|---|---|
| HBOS | High-Bandwidth Optical Services |
| HC | Horizontal Cross-connect |
| HCDS | High Capacity Digital Services |
| HCF | High Connection Failure |
| HCO | Hearing carry-over |
| HCT | Hierarchical Cellular Tree |
| HCV | High Capacity Voice |
| HDB3 | High-Density Bipolar Three-bit substitution |
| HDML | Handheld Device Markup Language |
| HDSL2 | High-bit-rate Digital Subscriber Line, Second Generation |
| HDT | Hawaii Dialogix Telecom |
| HDT | Host Digital Terminal |
| HEC | Header Error Control |
| HEHO | Head End Hop Off |
| HESC | Europian Harmonisation Short Codes |
| HETA | Health Electrification and Telecommunications Alliance |
| HFC | High Fiber Cable |
| HFC | Hybrid Fiber Coax |
| HFK | Hands Free Kit |
| HFT | Human Factors in Telecommunication |