Direct Inward Dialing (DID) allows businesses to route inbound calls directly to specific phones or extensions without going through automated menus. Companies purchase DID numbers from service providers and assign them to employees, eliminating the need for separate phone lines for each user. This streamlines the caller experience by connecting them immediately to the intended recipient.
How Direct Inward Dialing Works
DID functionality depends on the type of phone system a business uses—either Public Switched Telephone Network (PSTN) or Voice over Internet Protocol (VoIP).
DID on PSTN
- Traditional DID uses PSTN, where providers assign phone numbers based on the company’s location.
- Businesses must lease Primary Rate Interface (PRI) trunk lines from telephone providers.
- Each DID user gets a dedicated PRI trunk line connected to the company’s Private Branch Exchange (PBX).
- When a caller dials a DID number, the call is routed through the PBX to the correct extension.
- Limitations:
- Expensive hardware and bundled number purchases.
- Only 23 simultaneous calls allowed per PRI line.
DID on VoIP
- VoIP offers a flexible and cost-effective alternative using Session Initiation Protocol (SIP) trunking.
- DID numbers are virtual, assigned via cloud-based phone systems.
- Providers activate SIP trunking, linking DID numbers to users through software.
- Advantages:
- No physical hardware needed.
- Unlimited simultaneous calls.
- Quick setup (often same-day activation).
How to Get a DID Number
Getting a DID number is simple with a VoIP provider.
Steps to Acquire a DID Number:
- Choose a VoIP provider (many offer free business numbers with subscriptions).
- Log in to your account portal and navigate to the phone number ordering section.
- Select your preferred area code and choose from available DID numbers.
- Review costs (typically 5–5–40 per number, depending on type and location).
- Confirm and assign the number to a user or department.
- Test the DID number to ensure proper call routing.
Additional Options:
- Port existing numbers to your VoIP provider.
- Set up call queues, ring groups, or call forwarding for advanced routing.
Benefits of DID
DID offers several advantages for businesses:
✔ Better Flexibility
- Assign DID numbers to remote employees.
- Route calls to mobile devices or different locations.
✔ Improved Customer Service
- 77% of customers expect immediate contact (Salesforce).
- Eliminates frustrating call transfers and long menus.
✔ Simplified Internal Communication
- Employees can dial extensions directly.
- Useful for large organizations with multiple departments.
✔ Cost-Effective
- No need for physical phone lines or PRI hardware.
- Lower long-distance calling rates with VoIP.
