Telephone Code Index - 01438
| 742001 | 2001 Electronic Components Ltd. - Stevenage |
| 314753 | Alroy Microwave & Electronics Ltd. - Stevenage |
| 788500 | Avnet Emg Ltd. - Stevenage |
| 369466 | Campbell Collins Ltd - Stevenage |
| 740066 | Challenge Electronics Ltd - Stevenage |
| 743855 | Custom Electronic Design Services Ltd. - Stevenage |
| 730700 | Ets Lindgren Ltd. - Stevenage |
| 347570 | Flair Electronics - Stevenage |
| 813332 | G S Designs - Stevenage |
| 740400 | Gotec Trading Ltd. - Stevenage |
| 743753 | Lazerbuilt Ltd. - Stevenage |
| 220200 | LeoTel Software Systems Ltd - Stevenage |
| 316144 | Leyden Electrical Supplies (Stevenage) Ltd - Stevenage |
| 346600 | Nemco Ltd - Stevenage |
| 352657 | Omi TV Services - Stevenage |
| 350160 | P & E Skinner - Stevenage |
| 754477 | Precision Solutions MBDA UK - Stevenage |
| 749849 | QES Ltd - Stevenage |
| 761811 | Stevenage Circuits Ltd - Stevenage |
| 747309 | TIG Marketing - Stevenage |
| 842300 | Tmc Technology Uk Co. Ltd. - Stevenage |