UB was founded by Ralph Ungermann and Charlie Bass. Another leader in the company was John Davidson, vice president of engineering, who was one of the creators of NCP, the protocol suite of the ARPANET before TCP/IP.
UB specialized in large enterprise networks connecting computer systems and devices from multiple vendors, which was unusual in the 1980s. At that time most network equipment came from computer manufacturers and usually used only protocols compatible with that one manufacturer's computer systems, such as IBM's SNA or DEC's DECNet.
UB was one of the first network manufacturers to sell equipment that implemented Ethernet on twisted pair wiring. UB's AccessOne product line initially used the pre-standard StarLAN and, when it became standard, 10BASE-T.
UB was bought by Tandem Computers in 1988. UB was sold in 1997 by Tandem to Newbridge Networks. Over the next several months, Newbridge managed to lay off the bulk of the Ungermann-Bass employees, and closed the doors of the Santa Clara operation. Newbridge was later acquired by Alcatel.