| IFG | Inter Frame Gap |
| ICON | Inter Continental |
| IE | Inter Ethernet |
| IPG | Inter Packet Gap |
| IFS | Inter Frame Space |
| IBO | Inter Base Object |
| IC | Inter-LATA Carrier |
| IMT | Inter-Machine Trunk |
| ILU | Inter-Language Unification |
| ICT | Inter City Tilting |
| ICX | Inter Cartridge Exchange |
| IIC | Inter Integrated Circuit [Bus] |
| IBC | Inter Base Component |
| INL | Inter Node Link |
| ITC | Inter-Task Communication |
| ISI | Inter Symbol Interference |
| IRL | Inter Repeater Link |
| GIOP | General Inter-ORB Protocol |
| IPC | Inter Personal Computer |
| IOT | Inter-Office Trunk |
| INN | Inter Node Network |
| IRIS | Inter-Region Information Society |
| ISSP | Inter-Switch Signalling Protocol |
| SIFS | Short Inter Frame Space |
| TIPC | Transparent Inter Process Communication |
| ICE | Inter Client Exchange [Protocol] |
| ISSI | Inter-Switching System Interface |
| DIRC | Digital Inter Relay Communication |
| DIFS | Distributed/DCF Inter Frame Space |
| IATE | Inter-Active Terminology for Europe Luxemburg, http://iate.europa.eu |
| IAX | Inter-Asterisk Exchange Protocol |
| ICCC | Inter-Client Communication Convention |
| ICI | Inter/Interexchange Carrier Interface |
| EIFS | Extended Inter Frame Space |
| D6 | Inter Air [IATA-Airline-Code/ Südafrika] |
| PIFS | Point Coordination / PCF Inter Frame Space |
| CTIO | Cerro Tololo Inter-american Observatory La Serena, Chile, http://www.ctio.noao.edu |
| FOIRL | Fiber Optic Inter Repeater Link |
| IISP | Interim Inter Signalling/Switch Protocol |
| IOMC | Inter-Organization programme for the sound Management of Chemicals |
| IIOP | Internet Inter ORB [Object Request Broker] Protocol |
| EC | Heli-Inter [IATA-Airline-Code/ Frankreich] |
| H4 | Inter Islands Airlines [IATA-Airline-Code/ Kapverden] |
| 3P | Inter Tropical Aviation [IATA-Airline-Code/ Surinam] |
| IAI | Inter-American Institute for Global Change Research [engl.] Forschungseinrichtung der NSF |