Do you want to save money, improve customer service, and streamline your communication with your clients and prospects? If so, consider using Direct Inward Dialing (DID) for your business phone system.

But what exactly is DID, how does it work, and what are the benefits and challenges of using it?

In this comprehensive guide, we will answer all these questions and more. We will also show you what DID and DID numbers are and how to set up and manage your DID numbers effectively. By the end of this guide, you will have a clear understanding of what DID is and how it can help your business grow

So, let’s start with the definition of Direct Inward Dialing.

What is Direct Inward Dialing?

What is Direct Inward Dialing

Direct Inward Dialing, often abbreviated as DID, is a telephony feature that allows callers to reach a specific phone at a business or its department without going through an operator.

This is achieved by assigning a unique phone number to each extension within a Private Branch Exchange (PBX) system. Whenever a caller dials a DID number, the call is routed to the PBX system associated with that number, and the PBX system then directs the call to the corresponding extension.

Consider a company with a PBX system and multiple employees, each with their extension number. Without DID, callers would need to dial the company’s main number, wait for an operator or auto-attendant, and then provide the extension number they wish to reach. This process can be time-consuming and inefficient for both callers and employees.

DID eliminates this hassle by allowing callers to dial the extension number they need directly. 

What is a DID Number?

A DID number or direct dial-in (DDI) number refers to any phone number that provides a way for external callers to reach a certain internal extension number within the network directly rather than having to go through automatic routing or IVR systems

In essence, DID numbers are virtual numbers assigned by a telecommunication service provider to an organization. They act as a personalized shortcut, directing incoming calls straight to an individual user within a business instead to the entire phone system. 

If you want a DID number, there are two ways for you. You can go with either VoIP or PSTN-based direct-dial numbers. 

To get a DID number through PSTN, you need to contact a telephone service provider that can connect a block of telephone numbers to your company’s PBX system. Likewise, for a VoIP-based DID number,  you need to contact a VoIP provider that can connect a SIP trunk to your company’s phone system. 

How does Direct Inward Dialing work?

How does Direct Inward Dialing work

DID operates using either Public Switched Telephone Network (PSTN) lines or Voice over Internet Protocol (VoIP). In both cases, the working mechanism is a bit different. 

Direct dialing on PSTN

Direct dialing on the PSTN (Public Switched Telephone Network) relies on the numbering technique and routing infrastructure of the telecommunication network. Each telephone number is unique and serves as an address that guides the call through the network to reach the intended destination and the departments of the organization.

In PSTN, implementing direct inward dialing (DID) involves leasing and installing physical copper wires known as Primary Rate Interface (PRI) Trunks. These PRI Trunks are analog circuits that transmit call data from the provider, through the onsite Private Branch Exchange (PBX) system. 

After the call data passes through the onsite Private Branch Exchange (PBX) system, it is then directed to the specified user within the telephone company’s network. This user could be an individual or a department within the organization

Direct Inward Dialing on VoIP

Direct dialing works in VoIP by using a SIP trunk, which is a virtual connection between the VoIP provider and the public switched telephone network (PSTN). A SIP trunk allows VoIP calls to be transmitted over the internet instead of using copper wires. 

When a caller dials a direct dial number, the VoIP provider routes the call to the SIP trunk, which then connects the call to the appropriate VoIP phone or soft phone. 

The VoIP phone or soft phone can be registered with the VoIP provider using a SIP address, which is a unique identifier that links the phone to the direct dial number. 

How do you manage a direct inward dialing (DID) number?

Managing a DID number involves assigning, unassigning, and configuring processes. As already mentioned, to assign and unassign a DID number, you have to contact your phone service or a VoIP provider based on what type of number you are choosing. However, you have to be pretty strategic and clever while configuring your DID number. 

To configure your DID number, you have set up the routing rules by accessing your phone system’s settings. Additionally, a DID number can be set up to ring a specific extension or department, display a greeting message or menu options, display caller ID information, or take action if the call isn’t answered.

Here’s a cheat sheet for tips to manage direct inward dialing (DID) numbers. 

  1. Obtain a block of DID numbers and assign them to specific employees and departments of your organization. 
  1. Associate each DID number with an internal extension to your PBX to route calls to the appropriate internal extension. 
  1. Set up rules and specify how calls to each number should be handled, such as call forwarding, voicemail, or specific destination routing.
  1. Implement security features and regular checkups to protect against the misuse of DID numbers. 

Benefits of Direct Inward Dialing

Benefits of Direct Inward Dialing

Some of the benefits of Direct Inward Dialing are as follows.

Cost Saving

Direct Inward Dialing minimizes the demand for huge network infrastructure through the use of multiple dedicated phone lines that are expensive to install and maintain. Moreover, it can be used with VoIP technology that provides lower charges while maintaining superior call quality over long-distance and transnational communications. 

DID systems help with more efficient resource allocation as calls can be redirected to an appropriate department or person. It enables organizations and employees to allocate their time and money on legitimate questions and facilities rather than wasting it on irrelevant calls.

Direct Accessibility

Incoming calls can be sent directly to individuals or their respective departments using DID numbers without prior access through a central switchboard or receptionist. Communication is made simple, and delays are cut through the direct access afforded.

Similarly, DID numbers can be configured to make it possible for the users to access them remotely. The flexibility of remote work arrangements is enhanced by using the assigned DID numbers to call employees in various locations.


The presence of Direct Inward Dialing means that external players can dial up a given recipient without interruption. Thus, it provides a feeling that the customer is important and receiving personalized attention leading to a good impression of one’s profession.

A branding effort that incorporates DID numbers may emphasize the appearance of professionalism in a given business. For instance, sales teams could use separate DID numbers correlated with other marketing materials in order to provide callers with direct access to designated contacts.

Enhanced Call Management

One can provide DID numbers and add other features like call forwarding, voicemail-to-email, and call analytics. This ensures effective call management and unveils the communications trends.

Moreover, these DIDs can also be combined with CRM software as they relate to VoIP services. This provides an effective way for customer-oriented businesses to ensure seamless connectivity between calls and customer data.


To sum it up, Direct Inward Dialing (DID) stands out as a crucial asset in the complex world of telephony. Whether you’re navigating the traditional route through the Public Switched Telephone Network (PSTN) or embracing the innovative strides of Voice over Internet Protocol (VoIP), DID offers a straightforward way to reach specific extensions. 

The decision to adopt DID goes beyond just saving costs. Simply put, using Direct Inward Dialing (DID) changes how we communicate in business. It lets companies handle calls in a smooth and personalized way. When you think about adding DID to your communication system, see it as a vital part of making your business communication more effective and professional.


Can Direct Inward Dialing be used with VoIP technology?

Absolutely. DID is compatible with both traditional telephone systems and Voice over Internet Protocol (VoIP) technology. It seamlessly integrates with modern communication infrastructures.

What is Direct Inward Dialing (DID)?

DID is a telecommunications service that allows external callers to reach an internal extension directly within a private branch exchange (PBX) system without the need for a human operator. 

Is Direct Inward Dialing suitable for small businesses?

Yes, DID can be beneficial for small businesses as it facilitates direct communication with specific employees or departments, giving the impression of a larger and more professional organization.

What is the difference between DID number and Virtual Number?

DID (Direct Inward Dialing) number and a Virtual Number are terms often used interchangeably, but there are subtle distinctions. A DID number usually means a particular phone line linked to a business phone system. It lets you make direct calls to specific extensions.

In contrast, a Virtual Number is a more general term that includes different types of non-geographic phone numbers not connected to a physical line. This can involve DID numbers, toll-free numbers, or virtual extensions that send calls to specific places. 

In simple terms, all DID numbers can be virtual numbers, but not all virtual numbers are automatically DID numbers.

Can I customize the Direct Inward Dialing numbers for my business?

Yes, businesses can typically choose or customize their DID numbers within the allocated range. You can customize the digits contained in the number, call routing based on time, and problem, call forwarding on specific rules and conditions. This allows for branding, easy recognition, and aligning phone numbers with business strategies.

Passionate about optimizing online presence and crafting engaging digital content. Dedicated to enhancing user experiences through effective strategies.