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, think about what you'll need in 1-5 years. On the other 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.

The caveat there is the proverbial fine print, usually located just below the really attractive dollar figure. This small print generally details exactly how many months that nice number will remain in effect before the bloom comes off the rose and you start getting billed a much higher number that represents the service's actual cost. Many providers don't even print this higher number on their websites, so be sure to ask the sales guy on the phone before you sign up. The nice number that pulled you in can often double or more once the introductory period wears off. Some providers even attach a minimum length of time that you'll need to suffer these higher costs before you can change or modify the service without getting hit with an additional early-termination penalty fee.
However, for many businesses there's a need to route calls to the PSTN and other analog phones that might remain in use, too. This may mean a PSTN gateway, or even a hybrid PBX, where there's at least a small telephone switch located on-site. 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. Many small businesses, however, are avoiding on-premises PBXes 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 can handle PSTN connectivity without on-site hardware requirements.

On the phone providers' side, since this review roundup was first published, some of the products listed here now belong to other companies and some have merged into new products. If you're planning to depend on your phone system over the course of the next decade, then you should consider a vendor that's stable enough to still be around when it's time to up upgrade.

When shoppers ask which is the best VoIP service or who are the best VoIP providers, no two answers will ever be the same. Keep in mind, that the best service for one individual or business, might not be the most ideal for you. It’s all about finding a VoIP provider that can cater to your specific needs. Users should consider these factors when comparing VoIP providers:
Mobile clients are softphones optimized for a particular mobile OS and for being used in mobile situations. This means they're designed to switch easily between different cell and wireless connections on the fly. This means you can let your employees use whatever the cheapest wireless connection around them happens to be—and often that can be free. They also let your employees use your company's phone system on their own devices.
With all the features and functionality Nextiva includes, the fact that no plan exceeds 60 bucks a month is notable. A micro-sized office could get by easily with the bare-bones Office Pro setup, but the advanced features of Office Pro Plus and Office Enterprise are tempting for a few dollars more: the Nextiva mobile voice and video app and the Team Presence status indicator (both included in Office Pro Plus) are useful upgrades, as are call recording and the number-meshing Nextiva Anywhere app (Office Enterprise).
On the customer service front, RingCentral receives mostly positive reviews, offering phone assistance during standard work hours, 24/7 online chat service, and ticket service, in addition to weekly webinars and an extensive online knowledge base. Businesses of 20 users or fewer should note, however, that RingCentral favors larger enterprises for US-based support and outsources smaller-office support overseas.
BYOD stands for bring your own device. This term refers to employees conducting company business on personal laptops, tablets, and phones instead of on company-owned gear. Most VoIP companies offer BYOD features and solutions within their plans, either included or at additional cost. However, extra IT security layers and company guidelines for BYOD are on you.
Connectivity –VoIP is all about improved connectivity. That’s also a key factor when choosing a VoIP phone for your workplace. Phones which offer Wi-Fi connectivity are really handy – especially if you’re looking at cordless phones. They don’t require you to connect them up to your router via Ethernet. Models with built-in Bluetooth are great, too. They let your staff use hands-free headsets instead of handsets, giving them all the benefits of a mobile device.
Phone Power is another home VoIP provider that runs its service using an on-premises device. This is called the Home Adapter and like other services, it sits between your phones and your Internet connection, though no other network is required. It can even function as a router on its own. While it's not the cheapest home VoIP solution we found, it's certainly well-regarded and mature with a wide variety of options and capabilities.

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 a simple 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 of business-grade PBXes.  
The Yealink CP960 conference phone strikes an outstanding balance between ease-of-use and powerful features, delivering a smarter audio conferencing solution for your company. The Yealink Optima HD IP Conference Phone CP960, comprising the power of the Android 5.1 operating system. This Y-shape brand new release from Yealink combines simplicity of use with sophistication of features, being perfect for any team environment, especially for medium to large conference rooms. In regard of its crystal-clear audio quality, your conversation will sound natural and bright anywhere. You can connect an external loudspeaker to it if necessary. The Yealink CP960 provides wireless and wired pairing with your mobile staff – smartphone or PC/tablet via Bluetooth and USB Micro-B port.
A high speed Internet connection is required to "carry" your calls so if you have an Internet outage (or your ISP has an outage) then your phone service will not work. Internet services have improved significantly in the last few years and outages tend to be much less common than they use to be. Again, if you have a cell phone then this may not be an issue for you.
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