| 8101 | SOPJ | SOPGC | | | SCAC4 |
| 8102 | SOPK | SO-PAK-CO INC | | | SCAC4 |
| 8103 | SOPR | South Pierce R.R. | 1/1980-7/2005 | | NAKINA |
| 8104 | SOPR | South Pierce R.R. | 1/80-7/2000 | | NRHS |
| 8105 | SOPR | SOUTH PIERCE RAILROAD | | | PWRC |
| 8106 | SOPR | South Pierce Railroad | | | RSRV |
| 8107 | SOPV | STORMS OF PLEASURE | | | SCAC4 |
| 8108 | SOPZ | SORG PAPER COMPANY | | | PWRC |
| 8109 | SOQA | SOTELO, ADRIAN | | | SCAC4 |
| 8110 | SOQE | SLINKEMO ENTERPRISES LTD | | | SCAC4 |
| 8111 | SOQH | SOUTHERN HAULERS LLC | | | SCAC4 |
| 8112 | SOQI | SOUTHERN OIL COMPANY INC | | | SCAC4 |
| 8113 | SOQK | SCOTT, LOUIS TRUCKING INC | | | SCAC4 |
| 8114 | SOQP | SOSAS CAR CARE PRODUCTS | | | SCAC4 |
| 8115 | SOQQ | SALMON, PAT & SONS INC | | | SCAC4 |
| 8116 | SOQW | SOUTHWEST LOGISTICS INC | | | SCAC4 |
| 8117 | SOR | Air Stord A.S. | IATA: GO, Callsign: Air Stord, founded in January 1990. Ceased operations on 19 January 1999. | N | AVCODES |
| 8118 | SOR | SonAir Serviço Aéreo, S.A.R.L. | Callsign: Sonair, | ANG | AVCODES |
| 8119 | SOR | Sonair Servico Aereo | | | ICAO1 |
| 8120 | SOR | SOUTHWESTERN OKLAHOMA RAILROAD | | | PWRC |
| 8121 | SOR | Southern Ontario Railway | | | RSRV |
| 8122 | SOR | SOR s.r.o | | CZ | TRAFFIC |
| 8123 | SOR | Sortera, s.r.o. | | SK | VKM |
| 8124 | SORA | Southern Rails Cooperative, Ltd. | 1/1994-7/2005 | | NAKINA |
| 8125 | SORA | Southern Rails Cooperative, Ltd. | 1/94-7/2000 | | NRHS |
| 8126 | SORA | SOUTHERN RAILS COOPERATIVE LIMITED | | | PWRC |
| 8127 | SORA | Southern Rails Cooperative Limited | | | RSRV |
| 8128 | SORA | SOUTHERN RAILS COOPERATIVE LIMITED | | | SCAC4 |
| 8129 | SORB | SORM EXPORTS LLC | | | SCAC4 |
| 8130 | SORC | SORENSEN, CHAD | | | SCAC4 |
| 8131 | SOREC | Solenthaler Recycling AG | | CH | VKM |
| 8132 | SORF | SOUTH RIDGE FARMS LTD | | | SCAC4 |
| 8133 | SORG | SOLORIOS TRUCKING | | | SCAC4 |
| 8134 | SORI | SHORE ACRES ENTERPRISES INC | | | SCAC4 |
| 8135 | SORL | SORLIE TRUCKING | | | SCAC4 |
| 8136 | SORM | SORENSEN TRANSPORT | | | SCAC4 |
| 8137 | SORN | SORINI MANUFACTURING CORP | | | SCAC4 |
| 8138 | SORO | SOMA TRANSPORTES SC | | | SCAC4 |
| 8139 | SORP | SORENSON TRANSPORTATION COMPANY INC | | | SCAC4 |
| 8140 | SORQ | SOURCE ATLANTIC | | | SCAC4 |
| 8141 | SORR | SONRISE TRUCKING | | | SCAC4 |
| 8142 | SORT | SEA ORIENTATION SA PANAMA | | | SCAC4 |
| 8143 | SORTA | Southwest Ohio Regional Transit Authority | | USA | TRAFFIC |
| 8144 | SORU | SOUZ RAIL TRANS LLC | | RUS | BIC |
| 8145 | SORV | SOUTH RIDGE TRANSPORT LLC | | | SCAC4 |
| 8146 | SORX | Shaffer Oil & Refining Co. | 8/1920-7/1923 | | NAKINA |
| 8147 | SORX | Shaffer Oil & Refining Co. (Deep Rock Oil Corp.) | 7/1930 | | NAKINA |
| 8148 | SORX | Sorrells Farm Supply, Inc. | added 7/2002; 7/2005 | | NAKINA |
| 8149 | SORX | *SINCLAIR REFINING CO. [DEEP ROCK OIL CO.; SHAFFER OIL & REFINING CO.} | | | PWRC |
| 8150 | SORX | +SORRELLS FARM SUPPLY, INC. | | | PWRC |
| 8151 | SORX | Sorrells Farm Supply | | | RSRV |
| 8152 | SORX | SORRELLS FARM SUPPLY INC | | | SCAC4 |
| 8153 | SORY | SORCE, R | | | SCAC4 |
| 8154 | SOSA | SOSA GONZALEZ, BLANCA IRACEMA | | | SCAC4 |
| 8155 | SOSB | SMITH OILFIELD SERVICE INC | | | SCAC4 |
| 8156 | SOSC | SCARAN | | | SCAC4 |
| 8157 | SOSD | SOS METALS SAN DIEGO | | | SCAC4 |
| 8158 | SOSE | SOUTHERN STAR EXPRESS INC | | | SCAC4 |
| 8159 | SOSF | SIX ONE SEVEN FOUR THREE SIX (61743 | | | SCAC4 |
| 8160 | SOSG | SPECIAL OPS SERVICES INC | | | SCAC4 |
| 8161 | SOSJ | S O S TRUCK AND TRAILER REPAIR INC | | | SCAC4 |
| 8162 | SOSM | SONIC TRANSPORTATION SYSTEMS LLC | | | SCAC4 |
| 8163 | SOSN | SHELMIRE OIL SERVICE | | | SCAC4 |
| 8164 | SOSR | SOUTHSIDE TRANSPORT L L C | | | SCAC4 |
| 8165 | SOSU | STORAGE ON SITE LTD | | GB | BIC |
| 8166 | SOSX | Southern Oil Service | 7/1935 | | NAKINA |
| 8167 | SOSX | Southern Oil Service, Inc. | 7/1937-4/1947 | | NAKINA |
| 8168 | SOSX | Southern Oil Service | Apr-38 | | NRHS |
| 8169 | SOSX | SOUTHERN OIL SERVICE, INC. | | | PWRC |
| 8170 | SOT | Southeast Correct Craft, Inc. | Callsign: South courier, | USA | AVCODES |
| 8171 | SOT | Southeast Correct Craft | | | ICAO1 |
| 8172 | SOT | South Omaha Terminal Ry. Co. | 1/1975; eliminated 7/1978 | | NAKINA |
| 8173 | SOT | South Omaha Terminal Ry. Co. | 1/75; eliminated 7/78 | | NRHS |
| 8174 | SOT | SOUTH OMAHA TERMINAL RAILWAY COMPANY | | | PWRC |
| 8175 | SOT | SOUTH OMAHA TERMINAL RAILWAY | | | SCAC4 |
| 8176 | SOT | Sagami Railway (Sotetsu) | | J | TRAFFIC |
| 8177 | SOTA | SORTINO TRANSPORTATION COMPANY | | | SCAC4 |
| 8178 | SOTB | SCENE OF THE CRIME BOOKS | | | SCAC4 |
| 8179 | SOTC | STAR ON TIME EXPRESS LLC | | | SCAC4 |
| 8180 | SOTD | SCOTT TRANSPORTATION INC | | | SCAC4 |
| 8181 | SOTH | SOUTH OTAY TRUCK & HEAVY EQUIPMENT | | | SCAC4 |
| 8182 | SOTI | SORTINO TRANSPORTATION INC | | | SCAC4 |
| 8183 | SOTJ | SOTA TRANSPORTATION INC | | | SCAC4 |
| 8184 | SOTL | SOUTHLINE TRANSPORT, INC | | | SCAC1 |
| 8185 | SOTL | SOURCE ONE TRANSPORT LTD | | | SCAC4 |
| 8186 | SOTM | SOLO TOOL & MOLD LTD | | | SCAC4 |
| 8187 | SOTQ | SIX ONE TWO NINE SIX SIX EIGHT (612 | | | SCAC4 |
| 8188 | SOTR | SOUTHERN TRANSPORTATION SERVICES IN | | | SCAC4 |
| 8189 | SOTT | SCOTPAT LTD | | | SCAC4 |
| 8190 | SOTU | SOLETANCHE BACHY INTERNATIONAL | | F | BIC |
| 8191 | SOTX | Stoll Oil Refining Co., Inc. | 8/1920-7/1954; eliminated 4/1956 | | NAKINA |
| 8192 | SOTX | Southern Concrete Construction Co., Inc. | added 10/1997; eliminated 1/1998; 7/2000 (not listed) | | NAKINA |
| 8193 | SOTX | Stoll Oil Refining Co., Inc. | 4/38-1/52 | | NRHS |
| 8194 | SOTX | Southern Concrete Construction Co., Inc. | added 10/97; eliminated 1/98; 7/2000 | | NRHS |
| 8195 | SOTX | *STOLL OIL REFINING CO. | | | PWRC |
| 8196 | SOTX | *SOUTHERN CONCRETE CONSTRUCTION COMPANY | | | PWRC |
| 8197 | SOTX | Southern Concrete Construction | | | RSRV |
| 8198 | SOU | Southern Airways | Callsign: Southern Express, | USA | AVCODES |
| 8199 | SOU | South Pacific Airlines Ltd. | Callsign: Paradise, | HK | AVCODES |
| 8200 | SOU | Southern Airways | | | ICAO1 |
