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Post Dial Delay (PDD)

Post Dial Delay (PDD) in telecommunications refers to the delay or time gap between the moment a caller completes dialing a number and the moment the caller hears a ringing tone or any other type of response.

PDD is an important metric in assessing the quality of service in voice communications. 

  • User Experience Impact: PDD is crucial for user experience in telecommunication services. Long delays can lead to user frustration or confusion, as the caller might think the call isn't being connected or has failed.

  • Causes of PDD: Various factors can contribute to PDD, including network congestion, routing paths, interconnection delays between different carriers, and the time taken for call setup procedures by the telephony equipment.

  • PDD in VoIP Systems: In Voice over Internet Protocol (VoIP) systems, PDD can also be affected by factors such as IP network latency, codec selection, and session initiation protocols.

  • Measurement and Acceptable Levels: PDD is typically measured in seconds. The acceptable level of PDD may vary based on the network and the specific service level agreements (SLAs) in place. Generally, a PDD of up to a few seconds is considered normal, but it should not be excessively long.

  • Diagnosis and Troubleshooting: Diagnosing PDD issues involves analyzing the call setup process and identifying where delays occur, which can involve inspecting various network elements and carriers involved in the call routing.

Understanding and managing Post Dial Delay is important for telecom service providers to ensure a high level of customer satisfaction and maintain the quality of their voice services.

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