Key features of VoIP

This section describes the key features of VoIP.

• Basic call

  • Offer/Answer

  • Codec payloads

  • Comfort noise

  • Media QoS marking

  • Signaling QoS

  • DTMF

• Secure call

• Call forwarding

• Call transfer

• CLIP

• CLIR

• NAT/FW traversal

  • STUN

  • Symmetric signalling

  • Symmetric media

  • Open ports for RTP/RTCP traffic

  • NAT binding keep alive

• Hold

• Call waiting

• Emergency call

• RTCP extended reports for VoIP metrics

• Phone management

• Terms and abbreviations