| 1 | IST | Istanbul Airlines A.S. | IATA: IL, Callsign: Istanbul, Ceased operations on 25 August 2000. | TR | AVCODES |
| 2 | IST | Istanbul Airlines | | | ICAO1 |
| 3 | ISTB | ISLAND TUG AND BARGE LTD | | | SCAC4 |
| 4 | ISTC | ISLAND TRANSPORTATION CORP | | | SCAC4 |
| 5 | ISTF | IRON SPRINGS TRANSPORTATION INC | | | SCAC4 |
| 6 | ISTK | ISLAND TRUCKING | | | SCAC4 |
| 7 | ISTN | I S TRUCKING | | | SCAC4 |
| 8 | ISTT | INTERSTATE TRANSPORT INC | | | SCAC4 |
| 9 | ISTU | 1ST CONTAINERS UK LTD | | GB | BIC |
| 10 | ISTU | ITC MARITIME SA | | | SCAC4 |
| 11 | ISTV | IDAHO SPECIALIZED TRANSPORTATION IN | | | SCAC4 |
| 12 | ISTW | INTERNATIONAL SHIPPING & TRANSPORTA | | | SCAC4 |
| 13 | ISTX | North American Car Corp. | added 10/1959; 4/1961-1/1975; eliminated 10/1979; 1/1980 | | NAKINA |
| 14 | ISTX | Interstate Tank Car Corp. | 8/1920-10/1957; eliminated 10/1959 | | NAKINA |
| 15 | ISTX | North American Car Corp. | added 10/59; 4/61-1/80 | | NRHS |
| 16 | ISTX | Interstate Tank Car Corp. | 4/38-10/57; eliminated 10/59 | | NRHS |
| 17 | ISTX | NORTH AMETRICAN CAR CORP. [INTERSTATE TANK CAR CORP.] | | | PWRC |
