Interphase Tech ispan 5535 pri Manual Do Utilizador

Integrated Services Digital Network (ISDN) is an 
internationally agreed-upon standard for end-to-end digital 
communications over the public switched network. ISDN 
includes specifications for signalling, long-distance 
transmission, bulk subscriber lines, and individual subscriber 
lines.

Two types of ISDN service are currently available:

•  Basic Rate Interface (BRI)

•  Primary Rate Interface (PRI)

Both BRI and PRI ISDN services have two types of digital 
channels: one ISDN D channel and multiple ISDN B channels.

•  The ISDN D channel is generally used to transmit 

signalling and control information such as call-in-
progress, incoming-call, or call-accepted information. It 
transmits information at a rate of 16 Kbps.

•  The ISDN B channels transfer data (voice, circuit-

switched data, and packet-switched data) at a rate of 56 
or 64 Kbps, depending on the local ISDN network.

The ISDN Basic Rate Interface consists of three digital 
channels: one D channel and two B channels. These channels 
can be used simultaneously, and are often referred to as 2B+D.