This model offers SIP Specific Event Notification to transmit DTMF, and USES SUBSCRIBE and NOTIFY to realize the control to IP phone.

该模型利用事件通告机制来传送双音多频信号，通过SUBSCRIBE和NOTIFY两个消息来实现交换机对SIP终端的完全控制。

youdao

This model offers SIP Specific Event Notification to transmit DTMF, and USES SUBSCRIBE and NOTIFY to realize the control to IP phone.

该模型利用事件通告机制来传送双音多频信号，通过SUBSCRIBE和NOTIFY两个消息来实现交换机对SIP终端的完全控制。

youdao