ISDN是基于电路交换的数字化数据服务。其应用如下：
1) 为家庭用户提供高速因特网服务。一个标准的ISDN BRI信道能提供128KBPS的速率。
ISDN服务能够将两个64KBPS的信道合成一个128KBPS的线路。
2) 用做大规模拨号访问服务器的终端电路。ISDN PRI线路是将许多拨号用户连入一个访
问服务器的标准方法。ISDN PRI线路是一种能同时容纳23个用户的高速ISDN线路。通过一个
ISDN PRI线路连接到访问服务器上要比用23条独立的电话线直接连到访问服务器上更灵活和廉价。
3) 拨号备份。ISDN线路可用来给路由器提供备份数据通路。
Supported ISDN Switch Types
basic-1tr6 = German 1TR6 ISDN switches
basic-5ess = AT&T basic rate switches
basic-dms100 = NT DMS-100 basic rate switches
basic-net3 = NET3 ISDN and Euro-ISDN switches (UK and others), also called E-DSS1 or DSS1
basic-ni1 = National ISDN-1 switches
basic-nwnet3 = Norway Net3 switches
basic-nznet3 = New Zealand Net3 switches
basic-ts013 = Australian TS013 switches
none = No switch defined
ntt = Japanese NTT ISDN switches (ISDN BRI only)
primary-4ess = AT&T 4ESS switch type for the U.S. (ISDN PRI only)
primary-5ess = AT&T 5ESS switch type for the U.S. (ISDN PRI only)
primary-dms = 100 NT DMS-100 switch type for the U.S. (ISDN PRI only)
primary-net5 = NET5 ISDN PRI switches (Europe)
primary-ntt = INS-Net 1500 for Japan (ISDN PRI only)
primary-ts014 = Australian TS014 switches (ISDN PRI only)
vn2 French = VN2 ISDN switches (ISDN BRI only)
vn3 French = VN3 ISDN switches (ISDN BRI only)
vn4 French = VN4 ISDN switches (ISDN BRI only)