ISDN is an integrated service for data transmission via a digital telephone line. It can be used for sending and receiving of text, voice, video and images for seconds. ISDN replaces the analogue channel between you and the opposite side with a completely digital service. As such, ISDN provides end to end virtual digital connection. To the difference of analogue modems which must divide part of their capacity for error correction and data retransmission and thus decrease the actual bandwidth of the line, the ISDN line can use its whole capacity for data transmission. ISDN provides high speed. ISDN saves time and money.

How does ISDN work? ISDN divides the telephone line into 3 digital channels: 2 "B" channels and 1 "D" channel. "B" channels are used for data transmission with speed of 64 kb/s. "D" channel performs the admistrative work - switching or switching over the call and the communication with the telephone network. With two "B" channels two calls can be made simultaneously, although there is only one ISDN line.

How fast is the ISDN line? Each ISDN line provides two channels of 64 kb/s. This means speed of 128 kb/s, when the two channels transmit data simultaneously. This means that the time and the price of data transmission for many applications will be less than a quarter from these used from 28,8 kb/s analogue modem. As the analogue modem needs up to half a minute to establish a connection, ISDN can transmit data for a quarter of a second. If you would like to subscribe for this service, you have to contact the Marketing Department of the digital telephone exchange of BTK and Digital SystemS for assistance for the construction of your Internet ISDN access.

This service is available in: Blagoevgrad, Kazanluk, Kjustendil, Pazardzik, Pernik, Plovdiv, Sofia, Stara Zagora, Varna and Vidin

The prices for ISDN access are identical with the prices of the service PersonalEUnet, iCard, vCard

For actual prices and more information, Please contact us:

		Digital Systems' Offices
		order@digsys.bg