There are times such as year ends or contract ends when your business may need to change the number of phone lines that it is using. In this post, we cover 4 main cases of sizing your telephone system from schools, offices, and call centres. Whether you are looking to outfit your new school or new office with the right telephone system or are simply moving and need to relocate a system, contact us today for a free, no-obligation consultation.


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How many phone lines do I need for my business?


Image: By Lucasmascotto [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

The right number of phone lines depends on your individual scenarios, but, thankfully, there are general rules of thumb for different settings, including:

  1. Schools, Medical Clinics, or Labs
  2. Offices or professional organizations
  3. Inbound call centres
  4. Mobile field offices

What is a phone line?

When phones started to become available for mass adoption, physical wires would have to be installed on every phone within a house or building. This is where the term “phone line” came into usage. As you can imagine, this created an arduous amount of work every time a phone needed to be added, requiring a custodian or maintenance worker to physical install an outlet and wire.

Thankfully, now digital communications, wireless internet, and VOIP  phone lines can be created through a computer, essentially providing offices and institutions with an incredibly flexible way to enable phone systems.

How many phones do I need for my school, medical clinic, or lab?


Rule of thumb: a phone should be available in every room that facilitates interaction with a patient, client, or student.

Because school teachers, medical staff, or technicians often need to communicate with other team members, having a live phone in the room can help coordinate emerging issues.


If a school has 5 classrooms and an office reception area that, would mean the school should have a minimum of 6 phones in the building. Further, if there is a counselor’s office, another phone would be required as this would be another space that facilities interaction.

How many phones do I need for my office?

office phones

Rule of thumb: a phone should be available at every employee desk and conference room.

The assumption is that every employee should be able to make calls from his or her desk for business purposes and that an employer should provide this utility to every office staff person.


If there are 20 employee desks and two conference rooms, the office would require about 22 offices lines.

Emergency considerations: some offices and jurisdictions may require offices lines to have landlines provisioned. This is because landlines may be powered by a reserve energy source. In the event of a natural disaster, landlines stand a higher likelihood of functioning, but this should be verified by your telecommunications provider. (source)

How many phones do I need for a call centre?

call centre office

Rule of thumb: for colocated service centres, having a phone for each desk is the starting baseline.

Another approach to calculating the number of service agents required can be based on the level of service quality, defined by the amount of time it takes for your company to respond to a customer in the queue. It is important to set this metric first and determine whether your company aims for an average of 60 seconds to first response or 3 minutes or less. Based on the graphic provided by Call Centre Helper, organizations can tell that there are decreasing returns to adding more staff.

It is also important to note that modern contact centres aim for 90% of calls to be answered in 10-15 seconds, whereas cutting edge customer service centres have long been executing customer service using a distributed model.


Given a call centre with a staff of 100 employees, the call centre would require 100 lines to be provisioned, with additional lines for any conference rooms and executive offices located on site.

For an advanced method of calculating the number of service employees, see here.

How many phones do I need for mobile field offices?VOIP Hamilton

Rule of thumb: provide a cell phone for each field worker or provision similar to an office environment.

Historically, this approach to provisioning phones is based on mobile field sales staff that require coordination from a home office and the flexibility of going to customers directly, or visiting and inspecting company assets like oil rigs, energy generators, and other structures.


Given that there are 20 field staff covering an area, each of the staff would require a mobile communication device like a corporate cell phone.

What are some free options that work with Wi-Fi or cell phone?

Since the phone appeared, multitudes of apps have shown up to try and combat the decades-long and dominant telephone system. For companies on a tight budget, here are some great communication alternatives to get your project off the ground:

  • Skype is a free internet communications tool, as long as you have a connection you are good to go with others who also have a Skype account
  • Google hangouts is a great way to contact people from around the world, similar to Skype it can contact people with a Gmail account, but can also make free North American calls
  • Vibr allows users to call each other internationally and is popular in the UK and Africa
  • LINE is a popular chat, video, and telephone app connecting people internationally to one another
  • WhatsApp is another app that is popular among many people in North America and we’re surprised if you’re not already on this app. Similar features to LINE but more focused on communications rather than social media.

We choose the right solution for your team each time

Work with the trusted advisor in telecommunications in South Western Ontario.  Whether it’s plain old phone systems or the best VoIP telephone service, contact the professionals at Network Telecom. Our knowledgeable and experienced team has been in the telecommunications business for decades; we understand telecommunications. We can help you decide the best choice for your business and we can facilitate the changeover and fully train and support your staff with the switch. If you would like to know more about how many phone systems you need for your specific case, contact us today.