VoIP Resources VoIP Fundamentals Introduction to Business VoIP

How Many Phone Lines Do We Need?

by Kevin Bartley

In this post, we look at different interpretations of a VoIP line (such as one phone line, multiple extensions) to help you determine how many you need.

A 'phone line' is an old term that comes from traditional landline phone systems. However, in an era where most businesses use a hosted VoIP service, this phrase is used in many different contexts. In this blog, we'll examine a few different interpretations of a 'phone line' and help you answer the critical question: How many phone lines do you need in your office? If you're looking to understand how to setup one phone line, multiple extensions—you've come to the right place.

What Is a 'Phone Line' Anyways?

'Phone line' and 'line' were well-defined terms in the not-so-distant past. In relation to a landline phone service, a line is a physical wire in the wall that allows each phone to receive inbound/outbound calls. With a landline system, each office phone requires one of these physical lines to receive phone service.

VoIP phone systems do not require you to install physical wiring. VoIP desk phones connect to your Internet network via Ethernet cables. Softphones and webphones can connect to your VoIP phone system via wireless Internet. This allows you to access your business phone system from anywhere with an active Internet connection.

'Phone line' has been used for so long, it's simply entered the English language as a popular phrase. But VoIP phone systems don't use 'phone lines' in the traditional sense of the term. As such, a 'line' has come to mean many different things in the VoIP world.

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What's Your 'Line'?

So how many phone lines do you need in your office? This largely depends on how you're using the word 'line'. The questions below will help define what a line means to you.

  1. Are you trying to describe the number of employees who need a phone? (e.g. we have 20 employees, so we need 20 lines)
  2. Are you trying to describe the number of physical phones you need? (e.g. we have 15 classrooms, so we need 15 lines)
  3. Are you trying to describe the number of inbound/outbound calls that your organization can handle at one time? (e.g. we need ten lines for customers to reach our support team at all times)
  4. Are you referring to the number of phone numbers your business needs? (e.g. we need two lines, one for our New Jersey office, and one for our New York office)
  5. Are you trying to describe the number of simultaneous calls each person can accept? (e.g. we need each extension to be able to take up to six calls at a time)

Let's look at each scenario.

1. Line = Number of Employees

If you're referring to 'lines' as the number of employees in your office, then you're talking about the number of 'users' or 'seats'. In this scenario, each user typically has a phone and a unique extension, with the option of additional features like a voicemail box, call forwarding, and music on hold. This is how you can achieve one phone line, multiple extensions. 

2. Line = Number of Phones

Certain institutions may refer to 'lines' as the number of physical phones they need. This is usually the case for facilities such as schools and hospitals, where phones are apportioned per room, and not necessarily per person. Employees who frequently travel between offices may also have a desk phone at each location. In this case, the number of devices is greater than the number of users.

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Some VoIP providers allow multiple registrations to the same user, such as an office phone and a mobile softphone app. Both of these phones are 'assigned' to the user, and an administrator can set up call forwarding rules between them. If this is the case, you'll need fewer seats than the total number of devices registered to your network.

3. Line = Number of Simultaneous Inbound/Outbound Calls

Sometimes people use 'lines' to refer to the number of inbound/outbound calls an organization can take at one time. With a hosted VoIP solution, there are certain services that limit the number of concurrent calls you can make. But there are also services that allow for a high or unlimited number of simultaneous calls.

The maximum amount of simultaneous calls matters very much to call centers, support/sales queues, and other high volume call operations. Since these groups receive a large amount of inbound calls, and because their business models depend on reliable service, they tend to view 'lines' from a simultaneous calls perspective. If you're considering unlimited pricing plans, make sure to review the terms and conditions to see how many simultaneous calls per phone number your plan includes.

4. Line = Number of Phone Numbers

Traditionally, each office location needed a unique phone number. With VoIP services, multiple locations can share the same phone number with extension dialing. For example, you can setup an auto attendant that asks the caller to select which location they wish to reach - 1 for New York, 2 for New Jersey, etc.

Of course, there are cases where a business prefers to operate with multiple public numbers. In this case, the number of 'lines' you need is simply the quantity of phone numbers you wish to have.

5. Line = Per User Concurrent Calls

If you're referring to 'lines' as the number of simultaneous calls a single user can receive, the number is generally limited by the IP phone that you're using. The SIP address registered with the phone can receive as many simultaneous inbound/outbound calls as the phone can handle (usually 6 to 8). With one SIP address enabled on the phone, an employee could handle up to 8 simultaneous calls, after which the phone would relay a busy message.

How Many Phone Lines Do You Need?

As you can see, a ‘phone line’ can mean many different things depending on the context. In most cases, you’ll be referring to the number of phone numbers your organization needs. The other interpretations refer to details like the number of registrations per user and the number of simultaneous calls per phone number.

When researching VoIP providers, choose one that offers the most flexibility for the lowest cost. For example, a provider that allows for a high or unlimited number of simultaneous calls per phone number and multiple registrations per user means you'll be paying for fewer phone numbers and users. Depending on your call traffic, you may only need one phone number.

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