Directory Number (DN)
A Directory Number (DN) is the unique number assigned to a single phone line or extension in a telephone system.
Definition
A Directory Number (DN) is the unique number assigned to a single phone line or extension in a telephone system. In a Salesforce contact center, the DN is what identifies an individual agent's phone or workstation: when a call is routed to agent A, the call rings A's DN. The concept predates Salesforce by decades, dating to PBX architectures of the 1970s, but it remains relevant in modern contact-center deployments because each agent still has a phone (soft or hard) reachable at a DN.
DNs sit alongside DIDs and DNIS in the contact-center vocabulary. DID provides the inbound numbers customers dial; DNIS identifies which DID was dialed; DN identifies the destination extension that the call is routed to. In Service Cloud Voice on Amazon Connect, the DN concept maps to the agent's Connect login: each agent is identified by a username and a soft-phone endpoint that effectively acts as their DN, even if no traditional telephone number is involved.
How Directory Numbers fit modern Salesforce contact centers
DN versus DID versus DNIS
Each term identifies a different point in the call flow. DID: the inbound number a customer dials. DNIS: the signal that identifies which DID number was dialed. DN: the destination extension or line within the contact center. A call flow runs: customer dials DID, carrier signals DNIS, contact center routes call, call rings agent''s DN. All three are required for a complete contact-center deployment.
DN in legacy PBX contact centers
Before cloud telephony, a contact center had a PBX (Private Branch Exchange) with a numbered extension per agent. Each extension was a DN. The PBX held the routing logic: when DNIS signaled a sales call, route to the queue, then ring the next available agent''s DN. Salesforce contact centers built on legacy PBX (CTI integrations with Genesys, Avaya, Cisco, NICE) still use this model under the hood.
DN in Service Cloud Voice and modern cloud telephony
Service Cloud Voice (on Amazon Connect) replaces hard-extension DNs with soft-phone endpoints. Each agent has an Amazon Connect user and logs in through a soft-phone in the Service Cloud Voice console. The DN is effectively the agent''s Connect identity rather than a numbered extension. From a routing perspective, the behavior is identical: a call routes to the agent''s soft-phone, the soft-phone rings, the agent answers.
DN ranges and dial-plan management
In larger deployments, DN ranges are managed as part of the dial plan. A 4-digit extension block (4000-4999) for one office, 5000-5999 for another. Salesforce-side, the DN is stored on the User or Agent record as a phone field. Dial-plan changes (renumbering extensions) require coordination between the carrier (PBX or Connect) and Salesforce (User record updates).
DN and agent status management
Service Cloud Voice and other CTI integrations track agent presence: Available, On Call, After Call Work, On Break. The agent''s DN is the routing target while they are Available. Status changes (the agent toggles Break) update the routing engine to skip that DN until status changes back. This is the bidirectional handshake between Salesforce and the telephony layer that makes intelligent routing possible.
DN portability and SSO
In modern setups, the DN is increasingly tied to the agent''s Salesforce login rather than a physical phone. Single sign-on between Salesforce and Amazon Connect means the agent logs in once and inherits their soft-phone DN automatically. This is the trend: phones become disposable, logins become the routing identity. Hot-desking and remote work both rely on this decoupling.
DN in reporting and analytics
Per-DN reporting answers questions like average handle time per agent, occupancy per agent, and outcome by agent. Salesforce reports on the VoiceCall object expose the agent identity (effectively the DN) as a field. Compare DNs to identify high-performing agents, training opportunities, and capacity planning needs. Per-DN metrics are also key to compensation models tied to call outcomes.
How to assign a Directory Number to a Service Cloud Voice agent
In Service Cloud Voice, the agent''s DN is effectively their Amazon Connect user identity plus the soft-phone they sign into. Provisioning an agent involves creating both the Salesforce user and the corresponding Amazon Connect user.
- Create the Salesforce user
Setup, then Users, then New User. Provide the agent''s name, email, and assign a profile that includes Service Cloud Voice access. The Salesforce user is the primary identity.
- Provision the matching Amazon Connect user
In the Amazon Connect console, navigate to User Management, then Add new user. Match the Salesforce user''s email and assign the appropriate Routing Profile and Security Profile.
- Assign the Service Cloud Voice permission set
Back in Salesforce Setup, assign the Service Cloud Voice permission set to the new user. This grants the Voice console access and the soft-phone capability.
- Configure the agent''s Routing Profile
In Amazon Connect, the Routing Profile controls which queues the agent can take calls from. Set the queues, channel concurrency (typically 1 voice call, 5 chats), and priority order.
- Test the soft-phone login
Have the agent log into Salesforce, open the Voice console, and confirm the soft-phone shows Available. Place a test inbound call to a DID that routes to their queue; the soft-phone should ring.
- Document the agent''s effective DN
Record the agent''s Connect username and the queues they are routed to. This is the DN in the modern sense and the answer to how do I route a call to this agent.
The primary identity. Drives profile-based permissions and Salesforce data access.
The telephony identity. Drives routing profile, soft-phone access, and call handling.
Controls which queues the agent takes calls from. Effectively the agent''s call mix configuration.
Permissions within Amazon Connect, distinct from Salesforce profiles.
- Salesforce and Amazon Connect users are separate. Provisioning one without the other leaves the agent in a half-configured state where Salesforce thinks they exist but routing does not.
- Routing Profile changes take effect immediately. Switching an agent from Support queue to Sales queue mid-shift can produce surprising call assignments.
- Soft-phone connections need a working microphone and stable internet. Headset issues are the most common reason a properly configured agent cannot take calls.
- DN concepts from legacy PBX (specific 4-digit extensions) do not directly translate to Service Cloud Voice. Train agents on the soft-phone model if migrating from PBX.
Trust & references
Straight from the source - Salesforce's reference material on Directory Number (DN).
- Service Cloud Voice OverviewSalesforce Help
- Amazon Connect Agent ManagementAWS Documentation
Hands-on resources to go deeper on Directory Number (DN).
About the Author
Dipojjal Chakrabarti is a B2C Solution Architect with 29 Salesforce certifications and over 13 years in the Salesforce ecosystem. He runs salesforcedictionary.com to help admins, developers, architects, and cert/interview candidates sharpen their fundamentals. More about Dipojjal.
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