What is IDSL?
A. IDSL is a cross between ISDN and xDSL. As with ISDN, it uses a single wire pair to transmit full-duplex data at 128 Kbps and at distances of up to the Revised Resistance Distance range of 15,000 to 18,000 feet. IDSL also uses a 2B1Q line code to enable transparent operation through the ISDN “U” interface. IDSL is essentially a leased line ISDN Basic Rate Interface (BRI), or an ISDN BRI that is not switched and does not contain signaling (a D channel). IDSL and ISDN BRI use the same 2B1Q line modulation. On the router, this equates to putting the BRI interface in a leased line configuration. The line can be configured for a speed of 64 Kbps, 128 Kbps, or 144 Kbps. The frames that are going across the wire are standard High-Level Data Link Control (HDLC) frames. IDSL can be configured with Point-to-Point Protocol (PPP) or Frame Relay encapsulation for the leased line BRI interface. The easiest way to think about it is as if the BRI interface was a slow speed synchronous serial port. A
Internet Digital Subscriber Line, unlike dial-up, is a connection that is always connected to the Internet. On average, connectivity with IDSL is twice the speed of a regular dial-up connection. IDSL is a service that is based on Integrated Services Digital Network (ISDN) technology. ISDN is a system of digital phone connections that allows data to be transmitted simultaneously across the globe using end-to-end digital connectivity (IDSN allows multiple digital channels to be operated at the same time through the same regular phone lines used for analog lines). Because our exchange, C.R.S.T. Telephone Authority, supports digital connections, a digital signal is transmitted across the IDSL instead of a an analog signal. This gives a much higher data transfer rate than analog lines (an uncompressed data transfer speed of 128 kb/s). An advantage of IDSL is the improvement of response time for interactive applications (i.e. games). IDSL can go anywhere ISDN can, at a distance of up to 50,0
IDSL is a combo technology of ISDN (Integrated Services Digital Network) and DSL (Digital Subscriber Line) that transmits data in the digital form on a regular twisted copper pair telephone line at the rate of 144kbps slightly higher than ISDN, but significantly slower than most DSL services. IDSL provides an option to the user where DSL service is not available. IDSL is better than ISDN in terms of providing “always-on” connection and transmit data through a data network. IDSL does not charge per-call fee. It is available on the flat rate. IDSL has one drawback that it needs own telephone line that becomes expensive for the customer. The second line provides phone service.
