What Is Direct Inward Dialing (DID)?
Direct inward dialing is a business calling feature that lets an organization route inbound calls to specific people, devices, or departments, without needing a dedicated phone line for each one. You select a single (or a block of) virtual phone number, and you decide where each number rings: a single employee's extension, a department queue, or an auto-attendant menu.
DID is a standard feature on any hosted VoIP phone system, but it's not available on traditional 'POTS' (plain old telephone service) lines, making it one of the clearest advantages VoIP has over legacy phone service.
Why Businesses Use DIDs
Fewer physical lines. A single internet connection handles dozens (and more) of DID phone numbers, so you're not paying for a dedicated physical line per extension. That means no new wiring, no technician visit, and no additional cost when you add a new employee or department.
Direct access. A caller who dials an employee's DID number reaches that person's phone immediately, without having to go through an auto attendant menu or the 'press 1 for sales’ detour. For customers calling a known contact, this cuts call time and removes friction before the conversation even starts.
Flexible routing. The same pool of DID numbers can point anywhere you need: a single employee's extension, a ring group that rings several phones at once, or an auto attendant that routes callers by department. One number can even ring multiple registered devices at the same time, with a staff member’s desk phone, mobile app, and desktop app all ringing together.
Real-time changes. Call routing isn't fixed once you set it. Log into your provider’s web admin portal, pick a new destination for any DID number, and save. The change takes effect instantly, with no service call or waiting period.
Local presence. DID numbers are sorted and purchased by area code, so a business can offer a local number in any market it serves, even one without a physical office there. That local area code can make a cold call or support line feel more familiar to the person answering it.
How to Set Up a DID Number
- Browse available numbers. OnSIP publishes our available DID pool by area code.
- Purchase it in the Admin Portal. No forms to fill out, no waiting on a rep. Simply search for the area code and rate center you want, select the phone number to purchase, and find the number immediately available and active in your account.
- Set its destination. Point the number at an extension, a ring group, or an auto attendant (or any other OnSIP call feature that you wish) and change it anytime.
OnSIP and DID Numbers: You Choose Where to Send Your Phone Calls
OnSIP has an expansive pool of DID phone numbers that our customers can purchase at any time. We publish our DID pool so you can confirm beforehand if a local phone number is available to buy.
An OnSIP customer purchases a DID number directly from the OnSIP Admin Portal—there are no forms to submit, and you won’t have to wait around for an OnSIP representative to fulfill your request. In the portal, you can select the area code and rate center of the number that you want. Once the number is purchased, it is immediately available for use in your account.
In the Admin Portal, you can set the number up so that it rings the destination that you want.
How to Use a DID Number as Your Main Business Number
If the DID number is your main business number, you can set the number’s destination to be your receptionist’s phone. That way, all inbound calls to the number will go right to your receptionist.
You can also create an auto attendant menu and send inbound calls to it so callers can choose the department that they wish to speak to. If you give each of your staff members a unique extension, callers can dial the extension when they hear the attendant menu and be instantly sent to that staff member. This is how you can use one DID number for your business with as many extensions as you need.
Yet another option is to create a ring group of a few employees; when inbound calls are sent to the group, all of their phones will ring, ensuring that the first available employee can answer the call.
The possibilities are endless!
How to Assign a DID Number to a Specific Employee
If you assign the DID number to one employee, all inbound calls to that number will ring the specific employee’s phone(s). OnSIP allows up to 10 phone devices to be registered to 1 user. This means that an employee can have his office desk phone, home desk phone, OnSIP mobile app, OnSIP desktop app, etc., all registered at the same time. Any inbound call that he receives will ring all of his registered phones—he just answers the call on the phone device that is closest to him at the time.
And what’s more, you can change the destinations of any of your DID phone numbers in real time right in the Admin Portal. Just log in, pick a new destination for your particular number, and save. All inbound calls to the number will be instantly sent to the new destination.
Ready to Put Direct Inward Dialing to Work for Your Business?
The direct inward dialing call feature gives you full control over how every call reaches your team, without the cost or complexity of physical phone lines. Check OnSIP’s list of available DID numbers for ones that you need in your area code or contact our sales team and talk though any questions you may have.