VoIP features

Silence compression

To reduce the amount of voice traffic to be transmitted, VoIP can automatically detect the time ranges of silence in a conversation, stop generating voice traffic, and send a small number of silence packets within these time ranges.

Comfort noise

Silent gaps during a call can be filled by comfortable background noise.

QoS

As voice services are highly time-sensitive, the priority transmission of voice packets must be guaranteed. Some measures such as PQ, CQ, WFQ, CBQ, and RTP can be adopted on the sender side for this purpose. To ensure an adequate bandwidth for voice transmission, adopt the CAR mechanism to implement traffic classification and policing.

Fax over IP

Based on VoIP, the FoIP system is responsible for setting up of fax channels and receiving and sending fax data. FoIP implementation involves modulation and demodulation, fax protocol processing, and IP channel maintenance.

One-stage dialing and two-stage dialing

One-stage dialing and two-stage dialing are methods used to connect the calling user to the called number. If a PBX sends the called number to the VoIP gateway, the VoIP adopts the one-stage dialing to connect the calling user. If the PBX does not send the called number to the VoIP gateway, the VoIP gateway adopts the two-stage dialing and plays prompt tones to guide the calling user to enter information such as a called number.

Automatic busy-tone detection

Different PBXs are likely to play different busy tones with different frequency spectra. Therefore, it is hard to recognize a specific busy-tone feature. With the smart busy tone identification technology, the VoIP gateway samples, calculates, and analyzes the busy tones played by the PBX to distinguish matching tones. Implement busy-tone detection by configuring these parameters on interfaces.