| 1 | ISR | Israir Airlines and Tourism Ltd. | IATA: 6H, Callsign: Israir, | IL | AVCODES |
| 2 | ISR | Israir | IATA: 6H | | ICAO1 |
| 3 | ISR | Iowa Southern R.R. Co. | added 10/1987; eliminated 4/1990; 1/1994-7/2005 | | NAKINA |
| 4 | ISR | Iowa Southern R.R. Co. | added 10/87; eliminated 4/90; 1/94-7/2000 | | NRHS |
| 5 | ISR | IOWA SOUTHERN RAILROAD (CEASED OPERATIONS IN 1989) | | | PWRC |
| 6 | ISR | Iowa Southern Railroad | | | RSRV |
| 7 | ISR | IOWA SOUTHERN RAILROAD COMPANY | | | SCAC4 |
| 8 | ISR | Israel Railways | | IL | VKM |
| 9 | ISRC | Idaho & Sedalia Transportation Co. LLC | 7/2005 | | NAKINA |
| 10 | ISRC | IDAHO & SEDALIA TRANSPORTATION CO. LLC | | | PWRC |
| 11 | ISRC | IDAHO & SEDALIA TRANSPORTATION COMP | | | SCAC4 |
| 12 | ISRD | ITALIAN STATE RAILROAD | | | SCAC4 |
| 13 | ISRL | IGLESIAS STELL, RICARDO MANUEL | | | SCAC4 |
| 14 | ISRN | I S TRAN INC | | | SCAC4 |
| 15 | ISRP | IOSCO TRANSPORTATION INC | | | SCAC4 |
| 16 | ISRR | Indiana Southern R.R. Co., Inc. | added 10/1992; eliminated 10/1993; 1/1994 (not listed); added 7/1996; 7/2000-7/2005; eliminated 1/2008 | | NAKINA |
| 17 | ISRR | Indiana Southern R.R. Co., Inc. | added 10/92; eliminated 10/93; 1/94; added 7/96; 7/2000 | | NRHS |
| 18 | ISRR | INDIANA SOUTHERN RAILROAD CO. | | | PWRC |
| 19 | ISRR | Indiana Southern Railroad | | | RSRV |
| 20 | ISRR | INDIANA SOUTHERN RAILROAD COMPANY I | | | SCAC4 |
| 21 | ISRR | Indiana Southern Railroad | | USA | TRAFFIC |
| 22 | ISRT | INTERSTATE US TRANSPORTATION | | | SCAC4 |
| 23 | ISRU | ISR INVESTMENTS LIMITED | | CY | BIC |
| 24 | ISRU | ISR INVESTMENT LIMITED | | | SCAC4 |
