Multi-Line Phone Systems For Businesses

best office phone systems

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Don’t keep your customers and stakeholders waiting – answer more calls than ever with a multi-line phone system

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A single line phone system won’t give you the capacity to grow your business. It’s like a busy bar having just one person serving – customers will get tired of waiting, and simply go elsewhere. A multi-line phone system relieves the bottleneck, allowing more calls to come through, and more customers to be served.

‘Multi-line phone system’ is a very broad term, covering traditional, KSU (key system unit), and IP (internet-enabled) phone systems. Knowing which one is best for your business can sometimes feel like choosing a restaurant, but not knowing what type of food you’re after.

If you would like an overview of the different multi-line options, just skip ahead to our FAQ section. Alternatively, discover all you need to know in our breakdown of the best multi-line phone systems below.

The Best Multi-line Phone Systems

Traditional handsets, KSUs, and IP phones all sit under the multi-line phone system umbrella. Our pick of the best multi-line phone systems features one of each.

The best multi-line phone systems are:

  • VTech 4-Line Small Business System
  • NEC Keyphone SL1000
  • Poly VVX 601
Type of phone systemBest…Star Rating
VTech 4-Line Small Business SystemTraditionalFor small businesses
NEC Keyphone SL1000Traditional/digitalFor medium-sized businesses
Poly VVX 601DigitalAll-rounder

1. VTech 4-Line Small Business System

Best for small businesses

The Vtech 4-line phone system is a clever piece of kit. It supports up to four incoming lines – that’s four separate numbers – and also offers advanced digital functionality. All calls come through the main console, and are then met by an auto-attendant, which allows the caller to select the right extension number. With voicemail capabilities, customizable hold music, and four-party conferencing, the VTech 4-line phone system is the perfect option for growing businesses.

Our rating
Price: From $149.95


  • Supports 1 to 4 lines
  • Supports up to 10 units in total
  • Includes an auto-attendant


  • Not particularly scalable
  • Requires 4 separate phone lines

2. NEC Keyphone SL1000

Best for medium-sized businesses

The NEC Keyphone SL1000 KSU is fairly similar to a PBX – the only real difference is it doesn’t have the same expansion or configuration capabilities. The system can be as simple or as complex as you wish. Simple could be one KSU that hooks up to a traditional telephone line, while a complex setup may consist of up to four KSUs. This would give you scope to receive a huge volume of calls, and connect with a huge range of internet enabled equipment.

Our rating
Price: Available on request


  • Connects to your local area connection (LAN)
  • Huge scope to add lines and handsets - supports up to 128 extensions and 64 IP extensions
  • 8 redirect modes


  • Not as scalable as PBX
  • Not as many features as an IP phone system

3. Poly VVX 601

Best all-rounder

With 16 line keys and 4 soft keys (for features like transfer, conference and call park), the Poly (formerly Polycom) VVX 601 is at the top of its game. It offers HD voice, seamless third-party app integration, video playback, and conferencing – and this doesn’t make it particularly expensive, either. VoIP systems, including hosted and self-hosted PBX, are often far more cost-effective, as they only require you to purchase the phone handsets and software package – you should already have an internet connection!

Our rating
Price: From $205.31


  • Lots of handy business features
  • Video recording and conferencing
  • App integration


  • Relies on an internet connection
  • Small businesses may not require all the features on offer

Expert Verdict

The VTech 4-Line Small Business System sits firmly in the ‘multi-line phone system for small business’ category, while the NEC Keyphone SL1000 is perfect for SMBs and medium-sized businesses. However, it’s the Poly VVX 601 that sits nicely across all business scales.

While some businesses may struggle to justify such an advanced handset, VoIP phone systems do lend themselves to both small and large scale setups, and usually involve a monthly fee (like a phone contract), rather than a large initial investment.

Best 2-Line Phone Systems

2-line phone systems are the most basic of the multi-line system cohort. They are ideal for startups, companies with few employees, or those that receive a low call volume. For our money, the top two 2-line phone systems are:

  • AT&T 2-Line 2 Handset Answering System
  • Panasonic KX-TS208W 2-Line Corded Speakerphone
Type of PhoneBest…Star Rating
AT&T 2-Line 2 Handset Answering SystemDECT 6.0Cordless 2-line system
Panasonic KX-TG9581 Expandable Link2Cell SystemDECT 6.0For home workers

1. AT&T 2-Line 2 Handset Answering System

Best cordless 2-line system

For a basic phone system, this DECT 6.0 set from AT&T has a lot going for it. Featuring 2-line operation, two cordless handsets (can be expanded to up to 12 handsets), and a base set, it’s ideal for kitting out a small home business or startup. Offering up great connectivity range, plus the option to connect your cell phone via Bluetooth, this is also the ideal phone solution for mobile workers – why glue yourself to your desk when you don’t have to?

Our rating
Price: From $199.90


  • Download up to 6,000 phonebook entries
  • Ringtones for cell calls and landline calls
  • Built-in phonebook directory for up to 50 names and numbers


  • Not internet enabled
  • Very basic functionality

2. Panasonic KX-TG9581 Expandable Link2Cell System

Best for home workers

This DECT 6.0 handset is a solution for homes, offices, and – where we think it does best – home offices. Giving you the option to use one line for business calls and the other for home calls, it can help you keep business communications separate from your personal life – ideal for home workers. Plus, Link2Cell enables you to sync up to four cell phones, meaning you can take mobile calls using your handsets. This system also enables with three-way conferencing and PC calling.

Our rating
Price: From $179.95


  • Easily separate business and home calls
  • Advanced answering system
  • Block up to 250 bothersome numbers


  • Allows you to take mobile calls using your handsets, but not vice versa

Expert Verdict

These phones really are for people seeking a no-frills phone system. While 2-line phone systems are incredibly basic, they do allow home-workers to keep personal and business calls separate. That being said, many home-workers are now choosing to cross over to VoIP phones. This is because they’re so easy to scale, and easy to move if your business grows – plus you can still keep your business phone and home phone line separate!

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The Best 4-Line Phone Systems

4-line phone systems are far more office-friendly, offering you the option to have four separate numbers for four different departments. With the majority of setups allowing for around 10 handsets, it’s still very much a small business phone system. However, you can invest in some pretty high-tech handsets that will assist you with your call-handling.

The top 4-line phone systems are:

  • AT&T Expandable 4-Line Corded/Cordless Small Business Phone System
  • VTech 4-Line Small Business System Main Console
Type of PhoneBest…Star Rating
AT&T SynJ 4-Line Corded/Cordless SystemTraditionalCordless 4-line phone system
VTech 4-Line Small Business System Main ConsoleTraditionalFor innovative technology

1. AT&T SynJ 4-Line Corded/Cordless System

Best cordless 4-line phone system

Although more expensive than the VTech 4-line phone system, this catchily named offering from AT&T comes with some pretty advanced features. Call waiting, intercom, remote access, and an innovative voicemail system take this 4-line phone system up a notch.

With lots of five star reviews across the web, people are certainly happy with this phone system’s performance. And it still delivers on the auto-attendant front, too.

Our rating
Price: From $569.95


  • Lots of great features
  • Promises ‘crystal clear’ communication
  • Expandable by 10 handsets


  • Only supports up to 11 users...
  • ...But could be too expensive for small businesses

2. VTech 4-Line Small Business System Main Console

Best for innovative technology

The VTech 4-line phone system grows alongside your business, giving you the option to add new lines as your call volume increases. Choose from either a deskset or cordless DECT phones, and set up a call forwarding system that prioritises handsets in the order you prefer. This phone system has the additional benefit of a built-in auto-attendant, which not only makes your call handling more efficient, but makes your business appear more professional, too.

Our rating
Price: From $149.95


  • Expandable by up to 10 handsets
  • Includes an auto-attendant
  • Console is pocket-friendly


  • Only suitable for small businesses
  • Additional units are fairly expensive

Expert Verdict

4-line phone systems are by far the best to invest in if you’re a small business that isn’t quite ready to move over to VoIP. This is because they provide you with all the features you need to improve customer experience, without you needing to make a major change.

That’s not to say you shouldn’t make the leap to VoIP. It’s certainly something to consider if you think your business will outgrow four lines in the near future. IP phone handsets don’t need to be expensive, and a relatively small monthly fee per user provides you with a host of features that’ll raise your professionalism to a whole new level.

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The Best Multi-Line Phone Systems for Small Businesses

The truth is, all of the phone systems featured above are suitable for small businesses – it just depends on the type of small business you own, and what your business prospects are.

Ask yourself the following questions:

  1. Are you looking to significantly grow your business, or maintain its current size?
  2. Are you looking to move premises anytime soon, or will you be staying with your current workspace?
  3. How far are you prepared to go to to improve your customer service?
  4. How much will it cost to lease more lines, compared to moving to internet-based calls?

In a nutshell…

2-line and 4-line phone systems are great if you own a small business that is stationary – you don’t want it to grow in size, you know that you’re not going to move business premises any time soon, and you’re happy with the way it conducts its customer service.

However, if you weren’t sure how to answer any of the questions above – in other words, if you’re looking to grow, move, or improve your business – then VoIP may be a better solution.

Why Choose VoIP?

✔ It’s highly scalable – from one handset to thousands

✔ Have as many lines as you want – from one to over a thousand

✔ Benefit from heaps of useful call handling features

✔ Collect call data to improve customer service, as well as your sales figures

✔ Easily move the system with you, and keep your number!

✔ Benefit from HD calls and high quality video calls

✔ Make cheap overseas calls

✔ A software app allows you to use your mobile phone like your office phone

What’s the cost of a small business phone system?

Below is a rough guide to the initial phone system cost. These prices are based on system with 10 handsets, looking at the differences between 2-line, PBX, and VoIP phone systems.

Installation costHardware costTotal initial cost
2-line phone systemFrom $500From $580$1,080
PBX phone systemFrom $7,000From $800$7,800
VoIP phone systemFrom $10From $800$810

Why the difference in costs?

2-line systems require technicians and electricians to install cables and phone lines, which makes them fairly expensive for what they actually are.

A PBX phone system costs from $700 per user to install. This is expensive, and really only worthwhile if you have more than 20 employees (the bigger the system, the better the value). Many large companies choose a PBX system because it gives them the freedom to configure their phone system just-so, while benefiting from a huge range of business tools.

VoIP systems are cost-effective because they literally plug in and go – provided you have your broadband set up. Although VoIP phone hardware is generally more expensive than traditional phone hardware, companies tend to see a return on investment fairly swiftly.

Both traditional telephone system providers and VoIP providers will charge you a monthly fee based on the features you require.

To find out the cost of a small business phone system, simply fill in our form with a few details, and the best suppliers for your requirements will be in touch with tailored quotes.


What is a multi-line phone system?

A multi-line phone system is exactly what it says it is – a phone system that consists of more than one line.

For traditional business phone systems, this can be in the form of 2-line, 4-line, and even 6-line phone systems.

If you’re thinking digital, it can come in the form of a KSU unit, PBX, or VoIP system.

How do multi-line phone systems work?

That depends solely on the type of multi-line phone system you require. Multi-line phone systems can get pretty complicated, but in a nutshell, they work as follows.

A traditional multi-line business phone system works by feeding individual lines into a receiving console handset. This, by default, rings the phones connected to it. You’ll be able to see which line is ringing, and pick up that line if it’s for your department. For example, you can have one line for sales, one line for accounts, one line for customer services, and so on.

A digital multi-line business phone system works by feeding the phone lines into a central unit. This can be in the form of a KSU (key service unit), a PBX unit, or if you choose hosted VoIP, an offsite server. The caller is then greeted by an auto-attendant that directs the call to the right department.

Which multi-line phone system is right for me?

The best multi-line phone system for your business depends on a number of factors.

Think about the following:

  • How many employees do you have?
  • What is your call volume?
  • What are your growth plans?
  • Are you planning on moving office?
  • What features do you require?

The table below gives you a rough guide to which multi-line phone system you should choose based on your business size.

2-line4-lineKSUPBXIP (VoIP)
Very small business
Small business
Medium business
Large business

However, don’t forget to think about the other factors:

Growth plans

You could very quickly outgrow a 2-line or 4-line phone system, so think about investing in one that’ll give you the scope to add more lines and more handset units. A KSU system is a good option for this, as its slightly cheaper than a PBX. You should also think about hosted VoIP, as setup fees are low, and it’s super-easy to add additional handsets.


Any phone system with physical phone lines will be difficult and costly to move. So if you’re planning on moving premises in the near future, think about choosing a system that you can easily pack up and take with you. The only phone system that’ll allow you to do this is hosted VoIP – all you’ll need to do is plug it in, and connect it to the broadband connection in your new place.


2-line, 4-line, and KSU systems can limit you in terms of the features they have available. The table below compares the features of a traditional phone solution with a basic VoIP package.

2-line/4-line/KSU phone systemPBX/VoIP phone system
Call plan
Caller ID
Call forwarding
Call waiting
Call plan
Caller ID
Call forwarding
Call waiting
Call data
Advanced call routing
CRM integration
HD voice calls
Mobile softphone
Voicemail to email
Instant messaging

Multi-line vs PBX vs VoIP vs KSU – What’s the Difference?

2-line, 4-line, KSU, PBX, and VoIP all come under the multi-line umbrella. But while 2-line and 4-line phone systems are traditional setups – in that they connect to traditional phone lines – KSU, PBX, and VoIP phones use either a combination of a traditional phone line and an internet connection, or just an internet connection.


Because PBX and VoIP phones connect to the internet, they can provide you with a much wider range of business tools, including the ones listed in the ‘features’ section above.

KSU phones are the odd ones out – they offer the same set of features as traditional phones, because the handsets are fairly basic. The internet connection, in this case, only allows you to connect your phone system to your local area network, enabling it to talk to computers, fax machines, and any other potential devices hooked up to your network.

What’s Next?

There are a huge range of multi-line phone systems available, but hopefully, this article has helped you work out which one is best suited to your business.

To recap:
  • Traditional 2-line and 4-line phone systems are suitable for very small and small businesses
  • KSU systems are best suited to small and medium businesses that don’t require a huge number of phone system features
  • PBX systems are expensive; they’re best suited to medium and large businesses, or businesses that require a particularly specialist setup
  • VoIP phone systems are suitable for very small businesses, right up to huge enterprises. They’re truly scalable, and offer businesses heaps of useful features that’ll help them manage customer relationships and hone their sales funnel.

Pinning down the cost of a phone system is particularly hard, because there are lots of different factors involved. Installation fees, setup fees, hardware costs, and software packages are just some of the factors that contribute to the total cost.

If you’re wondering how much a phone system will cost your business, the best thing to do is to get in touch with suppliers. We’ve made this super-easy for you – just fill in our form with a few details about your business, and our system will match you with the best suppliers for your requirements.

Written by:
Aimee profile image
Aimee is Expert Market’s resident telephone systems and point of sale go-to. If she’s not writing about business products, you’ll find her daydreaming about dog walking on Dorset beaches.
Reviewed by:
James thinks all businesses can improve if they use the right technology. At Expert Market, he utilises his 4+ years experience as a researcher to offer specialised advice on a wide range of categories from CRM to Fleet Management.