Dialed Number Identification Service

DNIS (Dialed Number Identification Service) is a telephony service that identifies the phone number the caller dialed to reach the system. In a call center context, DNIS tells VICIdial which of its many DIDs the caller used, enabling the system to route the call to the appropriate inbound group, call menu, or agent queue based on the specific number dialed. DNIS is the complement of ANI, which identifies the calling party’s number.

How It Works in VICIdial

When an inbound call arrives at VICIdial through a SIP trunk or carrier connection, the DNIS information is carried in the SIP signaling headers — specifically in the “To” header or the Request-URI. Asterisk extracts the dialed number and passes it to VICIdial’s DID routing engine, which matches it against the DID configuration table.

VICIdial uses DNIS to implement flexible inbound routing. A call center might have dozens or hundreds of DIDs — different numbers for different advertising campaigns, geographic regions, product lines, or service tiers. DNIS allows a single VICIdial system to distinguish between all these numbers and route each call differently. For example, calls to the “Premium Support” DID can be routed to a high-priority inbound group with skilled agents, while calls to a “General Inquiry” DID go to a standard queue.

DNIS is also valuable for tracking marketing effectiveness. By assigning unique DIDs to different advertising channels (TV, radio, web, print), call centers use DNIS to determine which channel generated each inbound call, feeding directly into campaign ROI analysis and lead source attribution.

Why It Matters

Without DNIS, VICIdial would not be able to distinguish between calls arriving on different phone numbers — every inbound call would be treated identically regardless of which number the caller dialed. DNIS is the foundation of intelligent inbound routing, enabling differentiated service levels, marketing attribution, and multi-product support on a single VICIdial platform.

For call centers running multiple campaigns or serving multiple clients on shared infrastructure, DNIS is essential for call segregation. Each client or campaign gets its own DIDs, and DNIS ensures calls are routed to the correct agent group with the appropriate script and CRM screen pop. Accurate DNIS handling is also critical for billing in shared-resource environments, where call minutes must be attributed to the correct client based on which DID received the call.