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Enterprise VoIP platforms provide UC functionality in a single system

The shift toward mobile workforces has dramatically changed how VoIP is deployed. Learn about three popular VoIP deployment models and use case scenarios and how VoIP is only a single component in a much larger unified communications strategy.

The telephone is likely the oldest technology used in most offices today. Many enterprise organizations rely on common telephone functionality as their primary form of communication. But, with so many communication methods available, some business leaders are questioning the need to upgrade and maintain their VoIP platforms as a mission-critical business component.

For organizations in the early stages of researching the need for a modern, enterprise-grade telephony platform, this is a great place to start. Let's first examine what voice over IP (VoIP) is and how it has evolved.

The evolution of the business telephone to VoIP

The first business telephone systems consisted of an on-premises server known as a private branch exchange. Original PBX platforms used analog technology and connected to the phone company's public switched telephone network (PSTN) using analog circuits, such as plain old telephone service lines, or analog T1 circuits. The analog PBX was later replaced with digital technology. This provided a higher-quality call and enabled organizations to easily add business-oriented telephony features, such as voicemail, conference calling and shared lines.

Right around the time phone systems transitioned from analog to digital, data networks became popular within the enterprise. Because computer networks used IP, while analog and digital PBXs used proprietary communications methods, it meant businesses were forced to manage two separate physical networks -- one for voice and another for data.   

With few exceptions, most businesses today use a combined voice and data network that runs VoIP for calling. Connectivity outside the office commonly uses either legacy digital T1 circuits or more modern Session Initiation Protocol, or SIP trunks, to the PSTN using session border controllers.

VoIP can be deployed in one of three architecture models. First is the on-premises model, where an IP-aware PBX server is located directly on the corporate LAN. This model is similar to what's used in legacy analog and digital PBX systems. The second model is a modern SaaS VoIP system, where management, call and session control reside in the public cloud. Finally, some organizations are opting for a hybrid cloud architecture that combines both on-premises and cloud-based operation and management.

Editor's note

Using extensive research into the VoIP market, TechTarget editors focused this article series on 10 industry-leading business VoIP providers that offer on-premises and/or cloud-based VoIP, as well as combine unified communications functionality into a single communications system. Our research includes data from TechTarget surveys and reports from other well-respected research firms, including Gartner.

Enterprises trending toward mobile-first methodologies

As business needs change, so must the technology used to support business operations. One change that's evolving VoIP deployment architectures even further is a shift toward mobile workforces. Instead of requiring employees to work out of a corporate or remote office, mobile users can opt to work from their homes, a coffee shop -- anywhere they can access the internet.

Mobile workforces provide employee flexibility, improved work-life balance and potential cost savings for the company. This desire to shift users away from the corporate office has created a mobile-first mindset within the IT department. With a mobile-first mindset, technology decisions are made based on catering toward remote and mobile users, as opposed to employees that work out of a physical corporate location.

Previous VoIP systems were designed and built with a corporate-first strategy. Thus, we're beginning to see a shift away from on-premises deployments to SaaS and hybrid cloud deployments. Let's examine all three architecture models in more detail.

VoIP architectures: The pros and cons

Despite the move toward mobile-first technologies, on-premises VoIP architectures remain the dominant enterprise deployment model. This architecture consists of one or more communications and session border controller (SBC) servers deployed on the corporate network. Desk and conference phones reach out to the VoIP communication server and register to it. Once a communications channel is established over the LAN using IP, local servers manage call setup, teardown and routing. If a call needs to be routed to the PSTN, the communications server will typically forward the call to an SBC that acts as the facilitator between the private VoIP network and the PSTN.

On-premises VoIP platforms generally have a hefty upfront Capex price tag, because the on-premises VoIP communications server, SBCs and any desk and conference room phones must be purchased upfront. From an Opex perspective, this architecture model only requires payments to one or more PSTN service providers the organization partners with to provide external dial tone to the rest of the world. Additionally, most enterprise organizations will opt to purchase hardware and software support plans from the VoIP vendor they choose to deploy.

Large companies that can benefit from economies of scale are most likely to purchase, implement and operate their entire VoIP platform on premises. That means the IT department likely operates one or more private data centers and hires well-trained staff in the area of VoIP administration. On-premises systems also benefit from having most users working within the local LAN, as opposed to working remotely. Because remote users are required to access the VoIP communication server that's managed within the local LAN, they must access the corporate network using technologies such as IPSec or Secure Sockets Layer virtual private network (VPN).

Lastly, all security surrounding the VoIP platform is fully developed, deployed and maintained by corporate staff. Larger organizations sometimes prefer to manage data security themselves, as opposed to relying on a third-party.

Voice telephony using VoIP technologies is simply one communication method in a much larger unified communications portfolio platform that most enterprise vendors offer.

SaaS VoIP architectures, on the other hand, provide opposing pros and cons when compared to on-premises counterparts. For one, because the communication server resides in a public cloud, businesses don't have to pay for communications servers or SBCs as an upfront capital expense. Instead, they pay for user licenses as a monthly, annual or multiyear operational expense. The cloud provider manages the necessary VoIP servers as part of the license agreement.

Another benefit of a SaaS model is administration duties are significantly reduced. With on-premises products, an IT department must hire one or more VoIP admins to manage the day-to-day operations of the telephony system, including firmware updates, platform patching and internal call-routing configurations. All of these tasks are offloaded to the VoIP service provider in a SaaS model. Additionally, all platform security is managed by the provider. This can be beneficial for companies that don't have the required in-house skills to do it themselves.

That said, in the long term, as a company grows and requires more licenses, there will come a point where the cost of paying for a SaaS VoIP will become noticeably more expensive. Therefore, small and midsize organizations gain the most benefit using a SaaS model when looking solely at price.

Cloud-based VoIP platforms are more mobile-friendly compared with on-premises systems. Capabilities such as call signaling, setup and routing are handled by a server located on the public internet, so it really doesn't matter where end users reside. Nor is any type of remote-access VPN required. Additionally, most cloud-based VoIP services specifically cater to users on the go, with features such as softphone apps that can be downloaded and installed directly onto smartphones and tablets. While softphones are really nothing new, added care has been put into SaaS VoIP platforms for companies seeking a mobile-first strategy.

Clearly, there are benefits with either the on-premises or SaaS VoIP architecture models. In some instances, however, a business finds a combination of the two models is best. This is known as a hybrid cloud VoIP architecture. Midsize businesses that can benefit from economies of scale -- yet prefer a cloud-managed model -- are likely to choose this architecture.

In a hybrid model, the communications server still resides on the corporate LAN. However, the hybrid model provides many of the cloud administration and remote user benefits found in the cloud model. Additionally, much of the underlying infrastructure security is handled solely by the service provider, while some VoIP platform security options can be managed by the customer. Thus, hybrid models bridge the gap for companies that don't fit perfectly into on-premises or SaaS products.

Comparing on-premises, SaaS and hybrid VoIP
The pros and cons of the different VoIP architectures

The market for VoIP platforms

Voice telephony using VoIP technologies is simply one communication method in a much larger unified communications (UC) portfolio platform that most enterprise vendors offer. Other communications tools and application integrations may include the following:

  • team chat
  • web meetings
  • video conferencing
  • contact center
  • customer relationship management
  • AI chatbots

The current UC market has split into two major groups that offer on-premises and SaaS deployments. VoIP vendors such as Alcatel-Lucent Enterprise, Avaya and NEC have well-established on-premises VoIP product platforms. While these vendors may also offer SaaS or hybrid cloud options, they aren't considered major players at this time in the cloud collaboration space.

Newer entrants into the VoIP market, such as 8x8, Fuze, Microsoft, RingCentral and Unify, are all looking to establish themselves in the SaaS VoIP market. The SaaS market is driving new innovation -- and new revenue streams -- and is where the most competition resides today.

Cisco and Mitel are two vendors that have well-established and popular platforms that cater to those seeking on-premises or cloud deployment models. Both vendors have been in the enterprise VoIP space for decades and timed the SaaS and hybrid markets appropriately to provide customers with a cloud offering that rival the new upstarts.

Voice communication continues to maintain its mission-critical status in the enterprise, despite the plethora of add-on collaboration tools available, such as chat and web meetings. In most cases, a robust and flexible VoIP platform as part of a full suite of UC tools is an absolute must-have.

This was last published in January 2019

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