Bellcore then dragged AT&T and Northern Telecom representatives together to hash out a unified BRI specification, called National ISDN 1. This forced terminal equipment vendors to implement a third dia- lect-NI-1 was not as feature-rich as AT&T Custom, SO it mainly displaced Northern Telecom's custom flavor as the latter switches were upgraded [29]. Later, NI-2 added a common dialect for PRI. A considerable variety of ISDN products was introduced besides a variety of ISDN telephone sets. Videoconferencing systems migrated from an earlier "Switched 56" data service to ISDN. At least one company created a remote call agent's instrument, allowing its user to be part of his employer's automatic call distributor while connected via an ISDN line at a different location. (Many years later, this was suggested as a good example of a Voice over IP application.) Data gear was widespread. ISDN-to-Ethernet bridges were made by various companies, largely aimed at telecommuters: The Transmission Control Proto- col/Internet Protocol (TCP/IP) network protocol suite was not yet dominant, SO bridges, operating at a lower layer, could be used with Novell IPX, DECnet, NETBIOS, or TCP/IP. And a range of ISDN plug-in cards was made for desk- top computers. In Europe, a German-led effort produced the Common ISDN Application Protocol Interface (CAPI [30]) standard to allow programs on per- sonal computers to use ISDN cards without regard for underlying variations in the national protocol. This was never very popular in the United States, where the TCP/IP protocol suite was becoming standardized and PC-to-PC connec- tions were of little interest; domestic-market ISDN card vendors instead pro- duced drivers to allow their cards to be used with popular protocol stacks. ISDN's difficulties in the United States were not helped by other misfea- tures that made it difficult to use. For instance, the National ISDN-1 standard required that every ISDN BRI device identify itself to the network with the line's service profile identifier (SPID). The 