Directory Number (DN)
A Directory Number (DN) is a unique phone number or extension assigned to a telephone line, device, or user in a CTI (Computer Telephony Integration) system.
Definition
A Directory Number (DN) is a unique phone number or extension assigned to a telephone line, device, or user in a CTI (Computer Telephony Integration) system. DNs identify the physical or virtual location for incoming and outgoing calls in a telecommunications network.
In plain English
“A Directory Number is a unique phone number or extension assigned to a specific phone line, device, or user in a phone system. It's the address in the phone network that identifies where a call should go.”
Worked example
Naseby Realty has a 200-extension Cisco PBX. Each phone extension - including each agent's desk phone, the company main line, the after-hours voicemail box, and the conference room - is identified by a Directory Number (DN). When a customer calls the main line, the PBX maps the inbound DN to a routing rule; when an agent transfers a call internally, the destination DN identifies the target. In the Salesforce Call Center config, each agent's profile is mapped to their personal DN so the right person's softphone reflects the right line. DNs are the addressing system inside the phone network.
Why Directory Number (DN) matters
A Directory Number (DN) is a unique phone number or extension assigned to a telephone line, device, or user in a CTI (Computer Telephony Integration) system. DNs are the addresses that the phone network uses to route calls: each call is directed to or from a specific DN, and phone systems use DN information to identify endpoints, log call activity, and report on usage. In contact center contexts, DNs are often associated with specific agents, queues, or virtual destinations.
DNs are a foundational concept in telephony and matter for CTI integrations because they're how the phone system identifies who's involved in a call. When an inbound call arrives, the destination DN tells the system which agent or queue should handle it. When an agent makes an outbound call, their DN identifies them as the caller. In Salesforce Service Cloud Voice and similar CTI integrations, DN information flows through to call records and analytics, enabling reporting on per-agent and per-queue call volumes.
How organizations use Directory Number (DN)
Uses DN information from their CTI integration to attribute calls to specific agents in Salesforce reporting. Per-agent call volume reports drive coaching and capacity planning.
Maintains a DN-to-agent mapping that's automatically synced with Salesforce so user records always reflect current phone assignments.
Uses DN reporting to identify which queues are handling the most call volume, informing staffing decisions for peak times.
Test your knowledge
Q1. What is a Directory Number?
Q2. Why do DNs matter in CTI integrations?
Q3. What's a common reporting use of DN information?
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