| Acronym | Definition |
|---|
| IMSI | International Mobile Subscriber Identity |
| IMSI | International Mobile Station Equipment Identity |
| IMSI | International Mobile System Identifier |
| IMSI | International Mobile Station Identity (now International Mobile Subscriber Identity) |
| IMSI | International Microcomputer Software, Inc. |
| IMSI | International Mathematical Sciences Institutes |
| IMSI | International Maple Syrup Institute (Ferrisburgh, VT, USA) |
| IMSI | Idaho Maximum Security Institution |
| IMSI | Incident Management Systems Integration Division (US DHS and FEMA) |
| IMSI | Intelligent Multi-Sensor Integration |
| IMSI | Information Management Systems, Inc. |
| IMSI | Integrated use of new Microwave Satellite data for Improved ice mapping |