What is IDSL?
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.