When people dial into a company, they hope that they get someone live on the phone. But more importantly, they are hoping they get to the right person who can handle their question or issue.

It can get frustrating to people if they have to keep going through a receptionist or an automated attendant to get to the same person every time.  

That’s where Direct Inward Dialing (DID) comes in. Below we will look at DID, how it works, and the advantages and disadvantages of using it for your business.

So let’s begin!

What Is Direct Inward Dialing?

What is DID?

Direct Inward Dialing (DID) is provided by your local phone company or exchange carrier. They can provide your business with a set of telephone numbers so that customers can call a company’s private branch exchange (PBX).  

Using the Direct Inward Dialing feature, a business makes it simple for its customers to reach individuals because each workstation has its own assigned number. The most significant thing is that it doesn’t require a physical line into the PBX for each connection.

Let’s look at an example where a phone company rents out 50 phone numbers from their local phone company. These 50 phone numbers can be called over five different telephone lines.  

Essentially this means that the company now can handle five different concurring phone calls at one time. If any other calls should come in while the other five lines are occupied, the customer will get a busy signal, or they can leave a voicemail. 

Yet with the DID feature, the PBX will automatically switch over a call for a specific phone number to the appropriate person or desk. No automated attendant or secretary is needed. 

A direct inward dialing system can also be used for live voice connections, voicemails, and faxes. 

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What Is a DID Number? 

You probably wouldn’t be able to distinguish between a regular telephone number and DID number. But if you go behind the scenes, a DID number is a virtual number that leads the customer directly to the extension of a person or department in a company.  

These virtual, direct-dial numbers will point inbound calls to a business’s phone system. Once the call hits the system, the job of relaying the call to specific individuals within the company begins, and this is what makes this number “direct.” The VoIP phone system manages this entire process. 

How Does Direct Inward Dialing It Work?

How does DID work?

Direct Inward Dialing usually works through Voice over Internet Protocol (VoIP) or Public Switched Telephone Network (PSTN). Below we will look into both of them and how they work.

Voice Over Internet Protocol (VoIP)

Over the past several years, many business owners have switched from traditional phone systems to VoIP because it has allowed their business to expand and grow with all of the advanced features of the internet without needing physical phone lines and a bunch of expensive office hardware. 

When an office uses VoIP technology, it allows them to use direct-dial numbers with Session Initiation Protocol (SIP trunking). SIP trunking creates virtual links when a business needs them. 

If you compare this to a traditional copper wire telephone system, DID is extremely flexible and allows businesses to grow more efficiently using VoIP. 

If you are a startup company, for example, and are constantly hiring new employees, you may need to scale up quickly. You can do this by adding as many direct phone lines as you need to through a software back office portal provided by your VoIP provider.

Having access to an online portal to add phone lines makes it super quick and straightforward. There is no need to call the phone company and wait for a technician to come out and add extra trunk lines.

Public Switch Telephone Network (PSTN)

A Public Switch Telephone Network (PSTN) is essentially a telecommunications network that allows subscribers to various locations to communicate by voice. It’s essentially your good old fashion telephone company. You might have even heard the term “plain old telephone service” or (POTS).  

Old-school Direct Inward Dialing uses the PSTN. The telephone company will connect a group of trunk lines to a business’s PBX, and those numbers are then distributed to the customer as a direct-dial number. 

All inbound phone calls to these direct-dial numbers are forwarded to the PBX through the trunk line. Once the inbound calls get to the PBX, the call is sent to the correct person without having to go through an operator or an auto-attendant.

DID technology has come so far because when DID numbers first came out, the phone company would provide the DID services using Primary Rate Interface (PRI) circuits that would require a business to lease several trunk lines from their telecom company. This used to cost companies a lot of money. 

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Advantages of DID

How does direct inward dialing work?

There are several benefits when it comes to using direct inward dialing. Below are just a few of the primary benefits that your company will experience: 

  • Cheaper – saves a ton of money because businesses don’t have to add additional trunk lines for extra phone numbers. 
  • Saves time- DID is a great time-saver for inbound callers as well as operators because no interaction has to take place.
  • Better customer satisfaction – allows inbound callers to go directly to the person they are looking for or department. 
  • Better team communication and organization – By having direct phone lines in each department in your company, you will be more organized, and your team will experience better communication. 
  • You can set up local phone numbers.
  • Automated call-forwarding
  • More control over sending and receiving calls
  • Advanced time-setting capabilities
  • Use different vanity numbers for various marketing campaigns.


Adding the DID feature to your VoIP is a great way to provide better customer service and give your customers a way to reach people and other departments with less hassle. No one wants to talk to an operator every time they call into a company. DID will allow callers to bypass the phone queues and get straight to the person they want to talk to.