| 1 | SOF | Solis Aviation | Callsign: Solis, Ceased Operations. | BG | AVCODES |
| 2 | SOFB | SCHROEDER FARMS TRUCKING | | | SCAC4 |
| 3 | SOFE | SOFFE, M J COMPANY | | | SCAC4 |
| 4 | SOFH | STOLLER FISHERIES INC | | | SCAC4 |
| 5 | SOFI | SOUTHERN FREIGHT, INC | | | SCAC1 |
| 6 | SOFI | SOUTHERN FREIGHT INC | | | SCAC4 |
| 7 | SOFIA | CП Гpaдски пътничecки тpaнcпopт | City: Sofia | BG | TRAFFIC |
| 8 | SOFIB | Sofia Public Bus Transport Company | City: Sofia | BG | TRAFFIC |
| 9 | SOFIM | Sofia Metro | City: Sofia | BG | TRAFFIC |
| 10 | SOFIT | Sofia Public Electrical Transport Company | City: Sofia | BG | TRAFFIC |
| 11 | SOFN | SIX ONE FOUR NINE EIGHT FOUR (61498 | | | SCAC4 |
| 12 | SOFP | SOLARFECTIVE PRODUCTS LIMITED | | | SCAC4 |
| 13 | SOFR | SOUTHERN FLORAL COMPANY | | | SCAC4 |
| 14 | SOFU | CMA-CGM | | F | BIC |
| 15 | SOFU | SOFREDI | | | PWRC |
| 16 | SOFU | Sofredi | | | RSRV |
| 17 | SOFV | SRT OIL FIELD SERVICE LLC | | | SCAC4 |
| 18 | SOFW | SEVEN OCEAN FORWARDING SERVICES LTD | | | SCAC4 |
| 19 | SOFX | Sterling Oil & Refining Co. | 8/1920 | | NAKINA |
| 20 | SOFX | STERLING OIL & REFINING CO. | | | PWRC |
| 21 | SOFY | SPIRIT OF 76 | | | SCAC4 |
