H channel

An H- channel is in the early days of ISDN by ITU- T in the recommendations I.231.6, I.231.7 and I.231.8 standardized general transmission channel for circuit-switched transmission services to public telecommunications networks with higher data transfer rate than the B-channel. While the B-channel as a data transfer rate 64 kbit / s offers, the channel type H with data transfer rates of 384 kbit / s ( H0), 1,536 kbit / s ( H11), 1920 kbit / s ( H12 ) should enable high bit -switched services. H0 and H1 were backward compatible with the PDH hierarchy of telecommunications networks in the Asia-Pacific or North American countries, H12 to that in Europe. For leased lines H channels were provided without D - channel mediated H- channels should have a built- D channel with 64 kbit / s. Exchanges for this channel type were never developed due to lack of demand, so that the H- mediated channel has only on paper meaning; in old textbooks he can still be found. Even for dedicated lines of the H channel has not prevailed, it was not built NTPM that offered an H - channel for the connection of a terminal. To find on the market network terminations for leased lines with 2 Mbit / s, the interfaces are instead offer with variably adjustable bit rate: usually 50 bit / s to 2.048 Mbit / s The interface is in these usually run after those commonly used in data communication X.21, X.30, X.31 and V.35 standards, in addition to the electrical and structural (connectors) conditions, the rate adaptation and the signaling set between the network terminations on both sides of the state line. Meanwhile, there are those network terminations for SDSL.

• ISDN