Packet mode method and concentrator arrangement for data terminals served by an ISDN

Concentrator arrangement adapted to enable a plurality of synchronous or asynchronous data terminals to be served by a common ISDN data B channel to which said data terminals are connected via terminal adapters and a digital subscriber termination for transmission of data in packet mode, said data terminals being connected to said terminal adapters via digital interfaces and said terminal adapters being connected to said digital subscriber termination to obtain access to first and second ISDN data B channels and an ISDN signalling D channel via said digital subscriber termination, said arrangement comprising:

• means for establishing a transit connection between said first and second terminal adapters via said digital subscriber termination and the second ISDN data B channel,
• means for passing data packets to be transmitted in a first direction between the first data terminal and a common packet mode ISDN port via said transit connection, the second terminal adapter and the first ISDN data B channel, and
• means for passing data packets to be transmitted in said first direction between the second data terminal and said common packet mode ISDN port also via the second terminal adapter and the first ISDN data B channel,
• whereby data packets conveyed in said first direction between the first data terminal and said common ISDN port pass through said second terminal adapter of said second data terminal and through the first ISDN data B channel by which said second terminal adapter communicates with said ISDN port, and
• whereby packets conveyed in the same direction for both data terminals are conveyed by the ISDN first data B channel between said second terminal adapter and said common ISDN port, said ISDN first data B channel thereby functioning as said ISDN common data B channel.