由数字传输与数字交换结合而成，提供端到端数字连接，实现在同一个网络上承载多种业务的数字化电信网integrated services digital network; ISDN

• 可视电话在传输信道上可分为公用电话网型、综合业务数字网型等多种方式。

  Video calls can be divided into several methods based on transmission channel, such as public telephone network type and ISDN type.