The Best Business VoIP Providers for 2021

VoIP communications can spell the difference between the success and failure of your hybrid work strategy. We tested the top cloud-based VoIP players to help you find the right solution for your company.

Updated September 10, 2021

Our 10 Top Picks

Voice over IP (VoIP) systems dominate the small to midsized business (SMB) telephone market, and that's only grown stronger during the pandemic. Not just because they're cheaper than an on-premises PBX, but mainly because they're mostly software, which makes them far more flexible. There's nothing an old fashioned PBX can do that a VoIP system can't, but there's a very long list of things you can do with VoIP that just aren't possible using on-premises hardware.

VoIP systems, sometimes called cloud PBXes, can manage all your voice communications from a central web console no matter how many extensions you've got, where your employees are located, or even what devices they're using. Most systems also offer features like video conferencing and team collaboration. Put all that together with subscription-based pricing that's generally much cheaper than an old-fashioned, on-premises PBX, and VoIP remains one of the best communications investments any business can make, especially during the pandemic.

Still, COVID-19 won't last forever and hybrid work may not be right for your business, so keeping in mind core VoIP criteria is important. That means providing voice communications for employees at their desks once they start returning to the office. VoIP systems may also need to support a call center for sales or customer service and support; and they often need to connect with and through a host of other communications channels, such as conference calls, fax machines, mobile communications, text messaging, video conferencing, and wireless handsets.

On top of that, they're often expected to provide more advanced functionality through software, like shared meeting collaboration, voicemail to email transcription, and call recording. And lest we forget, many businesses still need a service that will connect to the public switched telephone network (PSTN).  

Because they're working across such a broad array of features and channels, many of today's phone systems are adopting the moniker of Unified Communications-as-a-Service (UCaaS). These are generally cloud-based, virtual PBXes (private branch exchanges) that include at least one (usually multiple) software clients to enhance their functionality on the web, desktop, and especially mobile devices. Even residential VoIP systems come with features that are simply impossible with a conventional telephone system.

How to Choose the Right VoIP System

Before you can start considering a brand, you need to figure out exactly how you want your business to use a phone system. Look at your existing phone system and decide whether you're going to simply keep all of it and bolt some VoIP functionality on top, retain only part of it, or replace the whole thing. Frequently, a total replacement isn't in the cards if only because some parts of your existing phone system can't be easily changed over to softphones or even desktop VoIP handsets.

For example, if you have a heavy manufacturing environment with outdoor activities, such as a steel fabrication yard or a landscaping company, your rugged old outdoor phones may be exactly what you need. You also need to decide what features of the existing phone system are required, and what features of a new phone system you feel are necessary to carry into the future.

When planning, it's important to include stakeholders from all the key parts of your business. Yes, this especially includes the IT staff and the data security folks since your voice calls will now be data communications. But it also needs to include the workers who'll actually be using the system to get work done, especially the work that drives revenue and engages customers.

These people have invaluable insights into what's actually needed versus what's simply cool and new. Remember, a VoIP system is much more than just a new set of phones; these platforms have very long feature lists, but many of those features can change your overall price so you need to know what you need and what you don't. For business-level users, figuring all that out starts with understanding what VoIP really is.

VoIP wireless handset being used
(Getty Images)

So What Is VoIP, Exactly?

VoIP is a method of digitizing voice signals, and then sending the digital voice information over an IP network. To accomplish this, the analog voice information is encoded using software called a codec. When it comes time to change the digital signal back to analog so that it's understandable, another codec does that job.  

For a VoIP system to work, it needs a means of routing calls between users or to the outside world. In a cloud-based system, this gets handled by a virtual PBX. In the cloud, this routing is managed by your VoIP provider, which is part of why you're paying them. Whatever vendor is supplying that is also running a large PBX operation in a data center somewhere, and slicing off a little of it to dedicate to your organization in exchange for your subscription fees.

You're essentially sharing a large PBX with that provider's other customers, but because these companies use multi-tenant segmentation, your PBX will appear dedicated to you. This engine will take care of routing calls on your VoIP network and out to others as well.

However, for many businesses, there's a need to route calls to the PSTN and other analog phones. This may mean a PSTN gateway, or even a hybrid PBX, where there's at least a small telephone switch located at your office. Your VoIP vendor will let you know if this is necessary at the planning stage. Note that these days, a PBX looks exactly like the other servers in your data center, except with an attached means of handling local and analog phones.

However, many small businesses try hard to avoid any on-premises PBX components. That's partially due to cost savings and partially because the capabilities offered by all-cloud systems are more than advanced enough for their needs. Some virtual cloud PBXes, for example, can handle PSTN connectivity without any on-site hardware requirements. Make sure you ask any potential VoIP service providers about this before committing.

How UCaaS Benefits Your Business

If all this is starting to sound like more trouble than it's worth, remember that turning your PBX into a software solution means a significant opportunity for flexibility and integration that you simply can't get any other way. After all, programmers can now treat your phone as an app. Where that's taken us is to the fast-changing UCaaS paradigm mentioned above. Here, VoIP providers, like the ones we've reviewed, provide additional software capabilities that are all implemented and managed from a single, unified console.

While the exact features offered in any particular UCaaS solution can change radically from vendor to vendor, most include options for video conferencing, shared meeting and online collaboration tools, integrated faxing, mobile VoIP integration, and device-independent softphone clients. That last one is especially important now because it means that your employees can download an app to their personal smartphone or company laptop and that app will mirror all the functionality of their corporate phone, including responding to calls coming into your business phone number and their extension in particular. For folks trapped at home by the pandemic, that's a perfect solution.

Softphones are at the heart of most UCaaS instances, and for many VoIP buyers, they're becoming the primary use case, sometimes completely obviating the need for physical handsets. Part of that is because they work as well on mobile phones and tablets as they do on desktop PCs or laptops. For workers in call centers, softphones are often the only tool because they're the front-end window to any CRM or help desk integration, which is nowadays a must-have for that job.

So, for example, a softphone can combine a telephone conversation with text chat and screen sharing, which means a conversation between two employees can seamlessly add more participants, handle private text chats between those participants while the call is still going on, and extend to a collaboration session in which the group shares screens, documents, and data—no prep, no reserved lines, just button clicks. In the case of a CRM integration, the system could recognize the customer's phone number or some other identifier and automatically pull up that record for the technician or salesperson answering the call. It can even alert a manager to monitor the call if it's an especially important client.

That's the basics of UCaaS, but the concept is constantly evolving to include more communication and collaboration technologies. Those capabilities also get tweaked to provide new benefits, sometimes general, sometimes aimed at specific verticals, like healthcare, for example. The key is integration. Voice is becoming integrated with other back-end apps, and UCaaS is making that easier. In fact, it's become so popular that it's seen rapid growth over the last several years as recent research from Statista bears out.  

Statista chart: UCaaS Projected Market Growth in US Through 2024
UCaaS Projected Market Growth in US Through 2024

That rich feature fabric can change radically between vendors, however. For example, RingCentral's softphone offers a long list of app integrations and features, including not just collaboration platforms, but bi-directional email and scheduling among other things. Line2's softphone client, on the other hand, is specifically designed to be simple so users can pick it up quickly, and it does this by mostly mirroring the buttons you'd find on a standard desktop handset. Two ends of the spectrum, but that means you need to be very careful when testing these apps to make sure you're getting not only what you need but in the right way for how your company does work.

Looking ahead to 2022, you'll see UCaaS extending into another sector of integration, namely desktop as a service (DaaS). Services like these will become popular for hybrid work because they let IT pros push out fully managed corporate desktops virtually so users can access them from anywhere and (almost) any device. Just like VoIP, DaaS solutions let IT pros manage those desktops from a web console. This makes deploying new desktops, removing unneeded ones, super simple.

The bigger DaaS providers, especially Microsoft with its newly announced Windows 365 Cloud PC service will start combining DaaS with productivity suite bundles. In Microsoft's case, this means one monthly charge for Windows 365 Cloud PC and a Microsoft 365 instance. It makes sense for a compatible VoIP instance, like Microsoft 365 Business Voice, to quickly become part of that bundle.

Getting the most out of not just basic VoIP communication, but all these UCaaS features, too, means understanding some of the technologies running underneath or next to VoIP. For most every VoIP installation, that starts with SIP.

Editors' note: Line2 is owned by J2 Global, the parent company of PhonespySoftware24's publisher, Ziff Davis.

What Is SIP?

The Session Initiation Protocol (SIP) is one of the underlying technologies that make VoIP possible. This is a text-based protocol similar to HTML. It's the most commonly used standard for setting up and controlling phone calls in most VoIP systems. You'll run across references to SIP in almost anything you do with these kinds of phone systems, especially when you're selecting any handset hardware you want to use.

There are still other legacy protocols around, and some non-SIP standards, including H.232. Other protocols that are still around are the Media Gateway Control Protocol (MGCP) and the Skinny Client Control Protocol (SCCP). The former is known for being overly complex and also that it doesn't support some of the functions that people need in their phones, like caller IDs. Cisco is the primary proponent of SCCP since they developed it. But even so, Cisco is currently phasing SCCP out in favor of the much broader SIP standard.

SIP is what's used for the vast majority of modern VoIP phone systems. It also handles phone service, video conferencing, and several other tasks just fine, which is why its use is so widespread. Where it has trouble is data security, but more on that in a bit.  

What makes SIP so popular is not only that it's deep and flexible, but also because it was purpose-built to engage in multimedia (meaning not just audio but also video and even text) communications over TCP/IP networks. For VoIP calls, SIP can set up calls using a number of IP-related protocols, including the Stream Control Transmission Protocol (SCTP), the Transmission Control Protocol (TCP), and the User Datagram Protocol (UDP), among others.

But it can also handle other functions, including session setup (initiating a call at the target endpoint—the phone you're calling), presence management (giving an indicator of whether a user is "available," "away," etc.), location management (target registration), call monitoring, and more. Despite all that capability, SIP is simple compared to other VoIP protocols primarily because it's text-based and built on an easy request/response model that's similar in many ways to both HTTP and SMTP. Yet, it's still capable of handling the most complex operations performed by business-grade PBXes.  

However, while understanding the basics of VoIP and SIP is important, setting one of these systems up will require some general network skills, too. For the best voice quality, your network will need to meet certain minimums levels of throughput for upstream and downstream data. In addition, you'll also need to meet a minimum latency number (that is, the time between when a signal leaves a remote computer and when your system receives it), typically measured in milliseconds. You'll also need a business-grade connection to the Internet if that's where your call traffic is going to go.   

Concept art depicting workers beneath multiple kinds of connections

Optimizing Your Internet Connection for VoIP

Most VoIP solutions will require stable and consistent internet connectivity at all your office locations where VoIP will be used. At the very least, your business phone system must have access to a business-class internet link, so discuss these needs with your company's internet service provider (ISP). This should be a dedicated link through a dedicated router if you expect your phone calls to sound as if they were coming from a business and not someone's home Skype connection. At a minimum, it's important to have a router that can create virtual LANs (VLANs) and also has the ability to encrypt your voice traffic. These days, you need end-to-end VoIP security for any call.

For larger systems, and for systems where security is critical for things like being compliant to vertical regulatory needs, your current internet connection might not be adequate. The internet doesn't do quality of service (QoS), and bandwidth can be unpredictable. Network congestion can ruin a conference call, and activities such as DNS hijacking can put your business and data at risk.

We all love the internet, but it's not necessarily the safest place for your business voice communications. If you fall into this category, remember that while the internet uses the IP protocol and VoIP runs over IP, that doesn't mean that VoIP must run over the internet. You can get all the UCaaS software benefits we've mentioned by running your voice network over dedicated lines. Sure, it'll cost more, but it will also ensure crystal clear voice quality as well as the ability to implement much-improved data security.

Managing VoIP on Your Internal Network

In addition to making sure your internet service can handle your VoIP traffic, you also need to make sure your local area network (LAN) can handle it. What makes network management tricky with VoIP is that if you simply drop it onto your network, that traffic will get processed the same as any other traffic, meaning your shared accounting application or those 20 gigabytes worth of files your assistant just moved to the cloud.

The problem there is that VoIP traffic is much more sensitive to network bumps and potholes than most general office traffic. That translates to garbled conversations, difficulty connecting over Wi-Fi, or (worst case) dropped and lost calls. If your business is small and your network is essentially contained in one or two wireless routers, then your configuration and testing headaches might be fairly easy (though still there). For medium and larger networks, these tasks can be complex and time-consuming, which translates into added cost in terms of man-hours.

Fortunately, most of the providers reviewed here have engineering staff that will contact you as part of your setup process to help your IT staffers test and optimize your network prior to deployment. That's definitely something we recommend, even if it costs extra, but there are steps you can take now to prep your LAN for VoIP and make the deployment process that much easier.

For one, be sure to understand QoS (mentioned above). This means going beyond understanding the concept and moving to how the networking equipment in your office -- or your employees' home offices if you're still at that stage -- can actually implement QoS. Most business-grade networking hardware will be able to handle QoS in more than one way, so testing which method will handle voice traffic more smoothly in your environment is important.

Next, you want to understand codecs. This technology is what really gives each call its voice quality because it controls both bandwidth usage and the voice data's compression. There are several proprietary and open source voice codecs, so know which is supported by your networking equipment. Then make sure those codecs are supported by your VoIP vendor, and then test different kinds to see what's most efficient.

Last, you'll want to take a close look at your current network monitoring tools. At its core, VoIP is simply a specific kind of network traffic, so in the end it'll be these tools that allow you to see that traffic and manage it across your network. Make sure that the tools you're using support VoIP's needs, especially around QoS, traffic analysis, and network congestion issues.

Once you've engaged with a VoIP provider, their engineers will help you determine the overall service grade of your network (look at that as your network's basic "VoIP readiness factor") and how to tweak their service and optimize your network so VoIP can run effectively over your infrastructure.

How COVID-19 Is Impacting VoIP

The pandemic has hit most VoIP installations very hard. That's because what we've discussed above has been mainly about optimizing one network, namely your primary office network, for VoIP traffic. Those steps mean significant work and time, both for your VoIP vendor's engineers as well as your IT staff.

But what COVID has done is move your VoIP system off of a single internal network with one big and well-managed internet connection out to dozens, hundreds, even thousands of small home routers where your home-working employees now need to use their softphones. Maintaining good call quality there has been one of the chief challenges faced by IT professionals since 2020.

The problem is maintaining control over your voice quality at so many different locations. Even if you've got several business-grade routers working in a bunch of branch offices, this problem is surmountable since (1) it's usually not overly difficult to provision those branch office routers remotely, and (2) the routers at those locations were chosen by your IT staff specifically because they work well with the routers at your primary location. That's not the case with home routers.

If you've still got a legacy voice system, meaning an on-site PBX with analog phones, then your only real COVID response will be call forwarding to your employees' home phones. That may or may not be acceptable to your employees, especially since these days many of them won't have an analog phone available, which means you'll need to do your forwarding to a personally-owned mobile phone.

If you've got a VoIP system, however, then you've likely got one of the aforementioned softphones as part of that service, and that's how most organizations are meeting the COVID challenge, as evidenced by a survey conducted last year by sister site, Spiceworks Ziff Davis:

COVID-19 poll conducted by Spiceworks Ziff Davis, March 2020

Softphones are perfect for the pandemic because using one means your employees can simply boot up their laptop or mobile device, install the softphone, strap on a headset, and they're good to go. Theoretically.

In reality, that's when you can bump into voice quality problems. Your IT staff not only can't control those home routers remotely, they often won't even know their capabilities. These routers were either chosen by the employee or by the employee's ISP, so even in a midsized company, you're looking at hundreds of different makes and models. Some will have more advanced features, like QoS, some won't. Those that do may also implement QoS and similar features in different ways.

All that makes configuring and managing home routers very difficult for IT personnel, but they'll still be faced with that task because if employees run into conversation problems over their softphones, their first call will be to the IT help desk. Shunting them off to the VoIP provider, or worse, the ISP isn't a good idea either. It'll likely cause employee frustration since those outfits won't be familiar with your company and they'll either refuse support or it'll take a very long time.

In practice, most businesses are simply handling this on a case-by-case basis since COVID is a temporary problem. Most home networks can handle the extra load as long as the employee makes sure that other latency-sensitive traffic, like gaming or video streaming, is kept to a minimum during the hours when they need to talk. If some home routers develop problems, IT staff simply build a queue and handle those one at a time. Sometimes they'll be able to access the router remotely with the employee's permission, sometimes they'll have to walk that employee through configuration steps to fix the problem. Sometimes the employee will just have to live with it unless the company springs for a new router or a higher bandwidth tier from the employee's ISP.

Future-Proofing Your VoIP Communications

Looking beyond COVID, VoIP makes the most sense for the vast majority of SMBs, not just because subscription costs are less expensive than buying on-site PBX hardware, but also because VoIP is the only way to keep up with evolving communication trends.

But with integration being at the heart of VoIP and UCaaS, you can't make a purchasing decision here without thinking about the future. On one side, consider each vendor carefully to see what they've done over the last half-decade in terms of product development and keeping up with VoIP and UCaaS trends. On the other side, think about what you'll need in the next five years.

At PhonespySoftware24, we've noticed two trends that almost all the vendors we've tested here mentioned as being important to their customers over that last year. That means they'll be important capabilities those vendors will want to add to their platforms in 2021 and 2022:

  • Mobility and 5G. While some VoIP services still offer mobile handsets, these devices seem to be on the downslope. After all, if talking while walking is your goal, why carry around a clunky handset when you should just be talking on your smartphone? Seamless voice switchover based on geofencing is one approach. So if your smartphone detects that it's inside your company's wireless network it can seamlessly engage your VoIP client over Wi-Fi, not your cell service and now you'll be making and receiving calls from both your personal calling plan as well as your business' VoIP service. This generally goes beyond simple calls to also include texts, voicemail-to-email, and collaborative online meetings.

    However, a little further down the road is ubiquitous 5G. When that happens several VoIP vendors seem bent on simply connecting their service to 5G so workers will be able to access their business VoIP service wherever they are and across any device as long as it's 5G compatible. While some vendors do this with current mobile technology, the latency limits around 4G calling often make it a sub-optimal experience, not just for video and collaboration, but often simple voice traffic, too. 5G is the first service that promises the bandwidth necessary to make true mobile UC a reality.

  • VoIP security. As touched on above, the underlying protocol for VoIP is SIP and it wasn't built with security in mind. This means hackers are taking advantage of several new attack vectors. One example is a denial of service (DoS) attack specifically on a phone service rather than the network as a whole. This will garble or drop your service because it results in your connection quality degrading, heavy latency, and system crashes. Caller ID spoofing is also becoming more common. This amounts to a phishing attack using a phone rather than an email. By calling workers with a caller ID that looks like it's coming from inside the company, hackers are able to get employees to cough up all kinds of sensitive information because they think they can trust the person at the other end of the call.

    Every vendor we spoke to during this round of testing mentioned security as a major sales and development factor over the next several years. Potential solutions include, managed call encryption with no service degradation, integration with identity management systems, and even artificial intelligence (AI) measures to detect and respond to attacks as they happen.

For at least the next two years, these trends are likely to become important selling points in most VoIP vendor-customer pitches. While that's great, be sure to fully understand what's being offered and how the vendor is going to go about delivering it. Is a 5G implementation truly standards-based or are there still some proprietary hardware or software components? Have much will any new security measures affect overall voice performance, and does the vendor fully support the changing security requirements in important industry regulations, like HIPAA and SOX?

If all this seems like a lot of homework, remember that it's well worth the effort. Just about anything you can picture a business needing from a phone or collaboration system can be delivered by a hosted VoIP PBX solution—and generally at a more affordable price than purchasing and maintaining your own on-premises PBX. It's just a matter of selecting the right solution for your business.

If you have questions about business VoIP, subscribe to PhonespySoftware24's BusinessWatch newsletter and join the [email protected] business community on LinkedIn, where you can ask vendors, other professionals like yourself, and PhonespySoftware24's editors.   

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About Wayne Rash

Wayne Rash

Wayne Rash's IT Watch Column: Wayne Rash is a freelance writer and frequent reviewer of enterprise hardware and software. He is also a Senior Columnist for eWEEK. Email him at [email protected] Follow him on Twitter @wrash.

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