The service provides the user with two 64kbps B channels, one 16kbps D channel and two analogue ports. B Channels are used to carry virtually any kind of digital information. The B channels are available for either voice, data, text or image calls, or any combination thereof. These B channel calls are seen as normal, independent telephone calls to separate destinations. The D channel will set up and control these B -channel calls. Part of the D channel bandwidth will in future also be available for the transmission of X. 25 packet data, The two analogue ports provided are used to connect conventional equipment such as analogue telephones and group 3 fax machines to the network.

On the customer's side of the NT up to eight different customer premises equipment can be connected. Up to five terminals can have unique directory numbers and sub addressing can be used to distinguish between applications per terminal,

The Telkom ISDN 2a Basic Rate Access will allow up to three of these terminals to communicate at the same time, using the two B channels at 64kbps and the available bandwidth on the D channel for X25 packet data.

BENEFITS and Features from Telkom ISDN 2a

• COST SAVINGS can be achieved in many ways. By using Video conferencing it will reduce travel costs to attend meetings, or by using bandwidth top-up to complement existing digital leased lines, thereby reducing the number of leased lines needed. Because ISDN provides Dialed digital connections it is no longer necessary to use dedicated lines to achieve digital speeds or connectivity.
• QUALITY on the ISDN is higher with clear calls and fast call set-up. Better voice telephone service because digital connections are virtually error-free.
• TIME SAVINGS are made where ISDN is used for file transfer with speeds of up to 10 times faster than modems connected to PSTN. Higher data speeds can be achieved, speeds up to 128kbps before compression.
• FLEXIBILITY is achieved by supporting Various kinds of information ie. Voice, data, images, video and more are all digitized and transmitted without error through the digital network. Up to eight devices such as telephones, computers, facsimile machines etc. can be connected on a single line.
• RELIABILITY and IMPROVED CUSTOMER SERVICE can be delivered by businesses through leased line backup by providing virtually continuous communications links.

Typical Telkom ISDN 2a Basic rate access