| Manufacturer | Site |
|---|---|
| Ultra | No web address |
| Umax | http://www.umax.com/ |
| UMC | No web address |
| Unbranded | No web address |
| Unicol | http://www.unicol.co.uk |
| Unisys | http://www.unisys.com/ |
| Unitech | http://www.unitech-adc.com |
| United Systems Software Company | http://www.unitedsystems.com |
| Universal | No web address |
| US Robotics | http://www.3com.co.uk/products/modems/index.html |
| Utax | No web address |