Question
What is Post-Dial Delay (PDD) and the threshold?
Applies To
- Voice API
- SIP
Answer
Post-Dial Delay (PDD) is the time difference between when a caller initiates a call and when they should hear the ringback tone. In SIP technical terms, it represents the time difference between the SIP INVITE and a 18x response, such as 180 Ringing or 183 Session Progress.
The telecommunications industry consider anything under 7 seconds as an acceptable PDD Post-Dial Delay (PDD).
If you're experiencing a PDD that exceeds 7 seconds, please submit a support request for further investigation.
Articles in this section
- RTCP Sender Reports (SR) and Receiver Reports (RR) for Voice Calls
- Ringback Tone (RBT)
- Which codecs does Vonage SIP Trunking support?
- What is Post-Dial Delay (PDD)?
- How does Vonage investigate Voice call connectivity issues?
- Troubleshooting Voice Call connectivity Issues
- Measures To Improve Virtual Number Spam Flagging by US Telecom Providers
- What types of DTMF are supported?
- Why does Caller ID show as potential spam?
- Can I display my name (CNAM) on the receiving party's phone for outbound calls?