ISDN is a switched digital modem service using a Network Terminator (NT). An ISDN plug uses an RJ-45 size.

Digital Speeds available on ISDN:

2x 64k B channels (total 128k available)
1x 16k D Channel

128K ISDN offers integrated voice, data, video and image transmission over a single telephone line, with vastly increased quality and data due to digital transmission.

There are three types of ISDN services offered in South Africa:

• ISDN 2 (Basic Rate Interface)
  

• ISDN 2a (Basic Rate Interface)

• ISDN 30
  
  

See here for the latest Telkom SA ISDN rates (as of 1-March-1999)

See HERE for TDK Global Pro ISDN Modem