Short Duration Percentage

Short Duration Percentage (SDP) is the proportion of outbound calls that are answered but last less than a defined threshold — typically 6 seconds. A high SDP indicates that called parties are picking up and immediately hanging up, which strongly suggests that the caller ID is being flagged as spam or robocall by analytics engines. SDP is a key indicator of outbound DID reputation health.

How It Works in VICIdial

VICIdial does not have a built-in SDP report, but the metric can be calculated from the vicidial_log table by querying for answered calls with a duration below the SDP threshold. Some VICIdial administrators create custom reports or use the analytics dashboard to track SDP by campaign, CID, and time period.

A “short duration” call occurs when the called party answers (or the carrier reports the call as answered) but the conversation lasts only a few seconds. This pattern typically happens when: the recipient sees “Spam Likely” on their caller ID and answers only to hang up immediately, the call is auto-answered by a spam-blocking app that disconnects robocall signatures, or carrier-level call treatment briefly connects before blocking.

SDP should be tracked per outbound DID to identify which specific numbers have been flagged. When a DID’s SDP exceeds 30-40%, it is likely flagged and should be rotated out of the CID pool.

Why It Matters

SDP is an early warning indicator for caller ID reputation problems — often signaling issues before the answer rate drops obviously. A DID can maintain a decent raw answer rate (because spam-blocking apps “answer” the call) while having a terrible SDP (because those “answers” hang up immediately).

Monitoring SDP by DID enables proactive number rotation before flagged DIDs waste significant dialing capacity. Combined with STIR/SHAKEN attestation monitoring and CNAM registration, SDP tracking forms a complete DID reputation management system. See the DID hygiene feature page for DID reputation monitoring and rotation strategies.