Unless you’re running a major business out of your house, chances are you won’t need or be interested in the ability to do video conferencing with dozens of people at the same time. The same goes for an auto attendant and business software integrations. First decide which features are priorities for you (unlimited calling, voicemail-to-email, international calling plans, etc.) and then take a look at what each company offers. After all, there’s no sense in paying for features that you don’t need. 
VoIP allows both voice and data communications to be run over a single network, which can significantly reduce infrastructure costs. The prices of extensions on VoIP are lower than for PBX and key systems. VoIP switches may run on commodity hardware, such as personal computers. Rather than closed architectures, these devices rely on standard interfaces.[12] VoIP devices have simple, intuitive user interfaces, so users can often make simple system configuration changes. Dual-mode phones enable users to continue their conversations as they move between an outside cellular service and an internal Wi-Fi network, so that it is no longer necessary to carry both a desktop phone and a cell phone. Maintenance becomes simpler as there are fewer devices to oversee.[12]
Therefore, VoIP solutions also need to handle MNP when routing a voice call. In countries without a central database, like the UK, it might be necessary to query the GSM network about which home network a mobile phone number belongs to. As the popularity of VoIP increases in the enterprise markets because of least cost routing options, it needs to provide a certain level of reliability when handling calls.
The receiver must resequence IP packets that arrive out of order and recover gracefully when packets arrive too late or not at all. Packet delay variation results from changes in queuing delay along a given network path due to competition from other users for the same transmission links. VoIP receivers accommodate this variation by storing incoming packets briefly in a playout buffer, deliberately increasing latency to improve the chance that each packet will be on hand when it is time for the voice engine to play it. The added delay is thus a compromise between excessive latency and excessive dropout, i.e. momentary audio interruptions.
Another legal issue that the US Congress is debating concerns changes to the Foreign Intelligence Surveillance Act. The issue in question is calls between Americans and foreigners. The National Security Agency (NSA) is not authorized to tap Americans' conversations without a warrant—but the Internet, and specifically VoIP does not draw as clear a line to the location of a caller or a call's recipient as the traditional phone system does. As VoIP's low cost and flexibility convinces more and more organizations to adopt the technology, the surveillance for law enforcement agencies becomes more difficult. VoIP technology has also increased Federal security concerns because VoIP and similar technologies have made it more difficult for the government to determine where a target is physically located when communications are being intercepted, and that creates a whole set of new legal challenges.[68]
Whether it's a dedicated bridge device or a special VoIP phone, you'll need something on the hardware side compatible with VoIP in order to access the technology's chief benefit: its software layer. It's at this layer where VoIP's advanced communication and collaboration features are enabled and how well the provider has leveraged those advantages will be directly reflected in how its proprietary hardware and back-end services are programmed. Whether it's a phone or a bridge, if you're worried about getting lost in technobabble when trying to setup your new phone service, remember that the best providers should be able to ship you pre-configured devices that shouldn't require much, if any, intervention on your part. With these, you simply plug them into your router or connect them to your Wi-Fi network and they'll go out and find the provider's network on their own. Just power them up, connect to your network, and wait for the light to turn green.
Local number portability (LNP) and mobile number portability (MNP) also impact VoIP business. In November 2007, the Federal Communications Commission in the United States released an order extending number portability obligations to interconnected VoIP providers and carriers that support VoIP providers.[33] Number portability is a service that allows a subscriber to select a new telephone carrier without requiring a new number to be issued. Typically, it is the responsibility of the former carrier to "map" the old number to the undisclosed number assigned by the new carrier. This is achieved by maintaining a database of numbers. A dialed number is initially received by the original carrier and quickly rerouted to the new carrier. Multiple porting references must be maintained even if the subscriber returns to the original carrier. The FCC mandates carrier compliance with these consumer-protection stipulations.
Government and military organizations use various security measures to protect VoIP traffic, such as voice over secure IP (VoSIP), secure voice over IP (SVoIP), and secure voice over secure IP (SVoSIP).[39] The distinction lies in whether encryption is applied in the telephone endpoint or in the network.[40] Secure voice over secure IP may be implemented by encrypting the media with protocols such as SRTP and ZRTP. Secure voice over IP uses Type 1 encryption on a classified network, such as SIPRNet.[41][42][43][44] Public Secure VoIP is also available with free GNU software and in many popular commercial VoIP programs via libraries, such as ZRTP.[45]

We think that’s understandable, though, considering Vonage offers top-notch customer support to match its top-notch phone systems. All Vonage customers enjoy 24/7 customer support and IT solutions. And with Advanced Vonage plans, business owners get Orange-Glove Setup of their phone systems. And in case you’re wondering, Orange-Glove Setup = white-glove setup, but, you know . . . orange to match Vonage’s colors.
VoIP service providers offer many highly advanced, next generation calling, texting, video, and conferencing features. Often these features are included, and are valuable assets every step of the way throughout your specific communication needs. Traditionally, many of the calling features now included with VoIP phone services were exercised by a human being operating a switchboard. Directing call traffic appropriately is vital to the success of any business. With Voice Over IP solutions, many of them are customizable to put your business at the pinnacle of efficiency and professionalism. Network features are designed to make sure your business never misses a beat – keeping your infrastructure at the tip of your fingers at all times.
SIP-T29G IP Phone is the most advanced model in the Yealink T2 series. It has a high-resolution TFT color display, delivers a rich visual experience.Yealink Optima HD technology enables rich, clear, life-like voice communications. Supports Gigabit Ethernet, a variety of device connections, including EHS headset and USB. With programmable keys, the IP Phone supports vast productivity enhancing features.
Another area of business VoIP support covers the growing number of mobile employees using softphones for sending and receiving calls from a laptop or mobile device. With a cloud-based PBX solution, you can have employees at different physical locations, including multiple time zones. This makes it easier to support longer business hours to cover your entire customer base. Most of the business offerings offer call routing based on the time of day and time zone.
Because of the bandwidth efficiency and low costs that VoIP technology can provide, businesses are migrating from traditional copper-wire telephone systems to VoIP systems to reduce their monthly phone costs. In 2008, 80% of all new Private branch exchange (PBX) lines installed internationally were VoIP.[9] For example, in the United States, the Social Security Administration is converting its field offices of 63,000 workers from traditional phone installations to a VoIP infrastructure carried over its existing data network.[10][11]
On 24 March 2020, the United Arab Emirates loosened restriction on VoIP services earlier prohibited in the country, to ease communication during the COVID-19 pandemic. However, popular instant messaging applications like WhatsApp, Skype, and FaceTime remained blocked from being used for voice and video calls, constricting residents to use paid services from the country’s state-owned telecom providers.[60]
Vonage Business is the biggest name in VoIP, and the good news is it’s a leader in residential VoIP too. Vonage has powerful, nationwide infrastructure, ensuring 100% uptime whenever you make or receive a VoIP call through your home IP phone or the Vonage smartphone app. All pricing packages are billed monthly, with no contracts. However, if you agree to be billed annually, Vonage will reward you with close to a 50% discount on your first 6 months.
For an extremely small business, especially one that’s just starting out, Ooma is a smart choice, as it provides all of the hardware and software you need to be up and running quickly. You don’t need a lot of know-how to start using Ooma, which is nice for a small business, where the owner likely has to wear numerous hats, including network management.
If that all is starting to sound more complex than it's worth, remember that turning your PBX into a software solution means significant opportunity for flexibility and integration that you simply can't get any other way. After all, programmers can now treat your phone like an app. Where that's taken us is to the fast-changing UCaaS paradigm (more on that below). Here, traditional VoIP providers, like the ones we review as part of this review roundup, provide additional software capabilities that are all implemented and managed from a single, unified console.
Throughout the developing world, particularly in countries where regulation is weak or captured by the dominant operator, restrictions on the use of VoIP are often imposed, including in Panama where VoIP is taxed, Guyana where VoIP is prohibited.[51] In Ethiopia, where the government is nationalising telecommunication service, it is a criminal offence to offer services using VoIP. The country has installed firewalls to prevent international calls being made using VoIP. These measures were taken after the popularity of VoIP reduced the income generated by the state owned telecommunication company.

A telephone connected to a land line has a direct relationship between a telephone number and a physical location, which is maintained by the telephone company and available to emergency responders via the national emergency response service centers in form of emergency subscriber lists. When an emergency call is received by a center the location is automatically determined from its databases and displayed on the operator console.

Private VoIP systems can be physical hardware PBX appliances, converged with other infrastructure, or they can be deployed as software applications. Generally the latter two options will be in the form of a separate virtualised appliance. However in some scenarios, these systems are deployed on bare metal infrastructure or IoT devices. With some solutions, such as 3CX, companies can attempt to blend the benefits of hosted and private on-premises systems by implementing their own private solution but within an external environment. Examples can include datacentre collocation services, public cloud, or private cloud locations.

In Oman, it is illegal to provide or use unauthorized VoIP services, to the extent that web sites of unlicensed VoIP providers have been blocked. Violations may be punished with fines of 50,000 Omani Rial (about 130,317 US dollars), a two year prison sentence or both. In 2009, police raided 121 Internet cafes throughout the country and arrested 212 people for using or providing VoIP services.[53]
The technical details of many VoIP protocols create challenges in routing VoIP traffic through firewalls and network address translators, used to interconnect to transit networks or the Internet. Private session border controllers are often employed to enable VoIP calls to and from protected networks. Other methods to traverse NAT devices involve assistive protocols such as STUN and Interactive Connectivity Establishment (ICE).
Similar to its popular small business VoIP solution, Ooma Office, the company touts its on-premises VoIP appliance to power its residential service. You'll find three versions of this device to choose from: the Ooma Telo, Ooma Telo Air or Ooma Telo 4G, but they all sit between your Internet router and your phones, making installation of this low-cost service plug-and-play.  
In 1999, a discrete cosine transform (DCT) audio data compression algorithm called the modified discrete cosine transform (MDCT) was adopted for the Siren codec, used in the G.722.1 wideband audio coding standard.[74][75] The same year, the MDCT was adapted into the LD-MDCT speech coding algorithm, used for the AAC-LD format and intended for significantly improved audio quality in VoIP applications.[76] MDCT has since been widely used in VoIP applications, such as the G.729.1 wideband codec introduced in 2006,[77] Apple's Facetime (using AAC-LD) introduced in 2010,[78] the CELT codec introduced in 2011,[79] the Opus codec introduced in 2012,[80] and WhatsApp's voice calling feature introduced in 2015.[81]

Yes it is really this simple. Just connect your telephone adapter to your home Internet by connecting a cable between it and your router or modem. Then connect your existing phone to the adapter and you should be good to go. If you decided to use your own adapter, you will likely be required to run a quick configuration script that is supplied by your service provider.