| 1 | IRR | Tara Air Line | Callsign: Tarair, | IR | AVCODES |
| 2 | IRR | Tara Air Line | | | ICAO1 |
| 3 | IRR | Iraqi Republic Railways Establishment | | IQ | VKM |
| 4 | IRRC | Iowa R.R. Co. | added 1/1982; eliminated 4/1988 | | NAKINA |
| 5 | IRRC | Iowa R.R. Co. | added 1/82; eliminated 4/88 | | NRHS |
| 6 | IRRC | IOWA RAILROAD CO. | | | PWRC |
| 7 | IRRC | Iowa Railroad | | | RSRV |
| 8 | IRRC | Iowa R.R. Co. | | USA | TRAFFIC |
| 9 | IRRS | International Rail Road Systems, Inc. | 7/2000-7/2005 | | NAKINA |
| 10 | IRRS | International Rail Road Systems, Inc. | Jul-00 | | NRHS |
| 11 | IRRS | INTERNATIONAL RAIL ROAD SYSTEMS INC | | | PWRC |
| 12 | IRRS | International Rail Road Systems | | | RSRV |
| 13 | IRRS | INTERNATIONAL RAIL ROAD SYSTEMS INC | | | SCAC4 |
