On the early ARPANET, real-time voice communication was not possible with uncompressed pulse-code modulation (PCM) digital speech packets, which had a bit rate of 64 kbps, much greater than the 2.4 kbps bandwidth of early modems. The solution to this problem was linear predictive coding (LPC), a speech coding data compression algorithm that was first proposed by Fumitada Itakura of Nagoya University and Shuzo Saito of Nippon Telegraph and Telephone (NTT) in 1966. LPC was capable of speech compression down to 2.4 kbps, leading to the first successful real-time conversation over ARPANET in 1974, between Culler-Harrison Incorporated in Goleta, California, and MIT Lincoln Laboratory in Lexington, Massachusetts.[71] LPC has since been the most widely used speech coding method.[72] Code-excited linear prediction (CELP), a type of LPC algorithm, was developed by Manfred R. Schroeder and Bishnu S. Atal in 1985.[73] LPC algorithms remain an audio coding standard in modern VoIP technology.[71]
Ooma is a popular VoIP solution for businesses, and now that there’s a residential option, Ooma is even a great option for you at home. With this new addition to its services, Ooma has traditional phone companies running scared. After all, you just can’t compare the features, quality, and service that you get from a top-of-the-line brand name like Ooma. To begin with, the service is totally free. You read that correctly; Ooma’s residential VoIP is totally free. If you need more advanced features, you’ll have to pay for them. But even the Premium plan is very affordable. With both plans, you’ll get crystal clear sound quality, basic features like call waiting, online call logs, call return, and 911 services bundled into the plan. More advanced features include voicemail forwarding and monitoring, Ooma mobile calling, international calling, and custom ring patterns.
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]
Editors' note: Line2 is owned by J2 Global, the parent company of PCMag's publisher, Ziff Media Group. If you have questions you need answered about business VoIP, then remember to subscribe to PCMag's Small Business Newsletter and join the [email protected] business community on LinkedIn, and you can ask vendors, other professionals like yourself, and PCMag's editors.   
You can use our quote request form at the top of the page if you’d like us to pair up with providers that best fit your needs. Unfortunately, we don’t generate quotes for residential VoIP providers at this time. Still, whether you’re looking for residential or business service, you can rest assured that you’ll save hundreds to thousands of dollars a year once you’ve switched to IP phone service.

Editors' note: Line2 is owned by J2 Global, the parent company of PCMag's publisher, Ziff Media Group. If you have questions you need answered about business VoIP, then remember to subscribe to PCMag's Small Business Newsletter and join the [email protected] business community on LinkedIn, and you can ask vendors, other professionals like yourself, and PCMag's editors.   
Yealink SIP-T54S is an easy-to-use Media IP Phone with a 2.8-inch color-screen and a distinctive appearance and structure. For its simplified and human-friendly design as well as user interface, it brings the IP phone and users more closer and unceasingly boosts the operating experience. With Yealink Optima HD voice technology, T54S enhances its audio quality via adding Opus audio codec, so that it delivers superb audio quality and crystal clear voice communications. Yealink SIP-T54S built with Gigabit Ethernet technology, a built-in Bluetooth and a built-in USB 2.0 port, enhancing collaboration and productivity.
In the United Arab Emirates (UAE), it is illegal to provide or use unauthorized VoIP services, to the extent that web sites of unlicensed VoIP providers have been blocked. However, some VoIPs such as Skype were allowed.[56] In January 2018, internet service providers in UAE blocked all VoIP apps, including Skype, but permitting only 2 "government-approved" VoIP apps (C’ME and BOTIM) for a fixed rate of Dh52.50 a month for use on mobile devices, and Dh105 a month to use over a computer connected."[57][58] In opposition, a petition on Change.org garnered over 5000 signatures, in response to which the website was blocked in UAE.[59]
Each provider will disclose international calling rates on their website and a list of features on their website. We give a standardized list for each provider (with explanations on our VoIP Calling Features page) but providers experiment with different features all the time. Check their website (using a link on their details page) to verify how each  feature works.
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.

Sometimes things don’t go exactly according to plan and it’s good to have all your bases covered. Check if the company you’re signing with has a money-back guarantee and to what extent they back up their promises. You should also favor one that has multiple avenues for customer service—around the clock if possible—and read online reviews about the customer service the company provides.
You can use our quote request form at the top of the page if you’d like us to pair up with providers that best fit your needs. Unfortunately, we don’t generate quotes for residential VoIP providers at this time. Still, whether you’re looking for residential or business service, you can rest assured that you’ll save hundreds to thousands of dollars a year once you’ve switched to IP phone service.

While home VoIP systems are fairly straightforward to set up and use, a VoIP system for all but the smallest of businesses can be quite complex, In addition to have multiple users, business VoIP systems have complex feature sets that are necessary to conduct business in today's world. In addition, a business VoIP implementation must take into account the existence of the data network, even though in most cases it won't share the same infrastructure. This will mean switches and routers optimized for voice traffic, and security that's suitable for both business and VoIP.


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 business use cases, like call centers or help desk operations, for example. The key is integration. Voice is becoming integrated with other back-end apps.
For instance, while AT&T offers landlines with unlimited phone calls for $33.99/month, with RingCentral you can get the Essentials plan, which includes unlimited phone calls starting at just $19.99 per person per month, and you can also enjoy a more extensive list of features. On Grasshopper, the introductory plan costs as little as $26/month, but that includes 3 extensions. With residential VoIP, you have a bundle of features you couldn't find with traditional landlines. Also, because of technology's continual advancements, the features continue to improve every year without a sharp rise in costs. VoIP for home use makes sense because you derive so much more value than what the traditional phone companies of today are offering.
Disclaimer: The information featured in this article is based on our best estimates of pricing, package details, contract stipulations, and service available at the time of writing. All information is subject to change. Pricing will vary based on various factors, including, but not limited to, the customer’s location, package chosen, added features and equipment, the purchaser’s credit score, etc. For the most accurate information, please ask your customer service representative. Clarify all fees and contract details before signing a contract or finalizing your purchase.
Grasshopper isn’t technically a VoIP and it isn’t technically for residential customers, but it offers basically the same service for a competitive price. Technically speaking, Grasshopper is a cloud-hosted system that works on top of your existing landline or cell service so voice quality doesn’t suffer. While there’s a technical distinction, customers shouldn’t notice the difference. Grasshopper is built for entrepreneurs and small business owners who work from home. The Partner package is suitable for families, as it includes 3 separate contact numbers with up to 6 extensions. 
In the case of a private VoIP system, the primary telephony system itself is located within the private infrastructure of the end user organisation. Usually, the system will be deployed on-premises at a site within the direct control of the organisation. This can provide numerous benefits in terms of QoS control (see below), cost scalability, and ensuring privacy and security of communications traffic. However, the responsibility for ensuring that the VoIP system remains performant and resilient is predominantly vested in the end user organisation. This is not the case with a Hosted VoIP solution.
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]
Such emergency services are provided by VoIP vendors in the United States by a system called Enhanced 911 (E911), based on the Wireless Communications and Public Safety Act of 1999. The VoIP E911 emergency-calling system associates a physical address with the calling party's telephone number. All VoIP providers that provide access to the public switched telephone network are required to implement E911,[34] a service for which the subscriber may be charged. "VoIP providers may not allow customers to "opt-out" of 911 service."[34]

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]


VoIP endpoints usually have to wait for completion of transmission of previous packets before new data may be sent. Although it is possible to preempt (abort) a less important packet in mid-transmission, this is not commonly done, especially on high-speed links where transmission times are short even for maximum-sized packets.[18] An alternative to preemption on slower links, such as dialup and digital subscriber line (DSL), is to reduce the maximum transmission time by reducing the maximum transmission unit. But since every packet must contain protocol headers, this increases relative header overhead on every link traversed.[18]
For larger systems, and for systems where security is critical, the old internet connection is no longer adequate. The internet doesn't do quality of service (QoS), and bandwidth can be unpredictable. Network congestion can ruin a business phone call, and activities such as DNS hijacking can put your business at risk. While we all love the internet, it's not necessarily the safe place for your business voice communications. If you fall into this category, remember that while the internet runs using the IP protocol and VoIP runs over the IP protocol, that doesn't mean that VoIP must run over the internet. You can get the same software benefits of VoIP by running your voice network over dedicated lines. Sure, it will cost more, but it will also ensure crystal clear voice quality as well as the ability to implement much-improved data security.

In India, it is legal to use VoIP, but it is illegal to have VoIP gateways inside India.[61] This effectively means that people who have PCs can use them to make a VoIP call to any number, but if the remote side is a normal phone, the gateway that converts the VoIP call to a POTS call is not permitted by law to be inside India. Foreign based VoIP server services are illegal to use in India.[61]
To help businesses work from home, RingCentral provides unlimited internet faxing and audioconferencing on all the plans listed above. Video meetings can include up to 100 participants, and meetings can last up to 24 hours—just in case your group needs to burn the midnight oil. Standard plans and higher also include popular communication integrations like 365, G Suite, and Slack.

First, there might be a very low cost or even free "basic" or "introductory" tier that's just so feature poor that the vast majority of customers will opt for the next level up, which will be the full-priced tier. Another common practice is a one- or two-year contract, each with a slightly lower price that are offered next to a significantly higher-priced month-to-month tier. Additionally, while most residential VoIP services offer unlimited calling, some vary their pricing on call restrictions. Those will come either in the form of minutes (with higher pricing attached to monthly overages) or geographic region. The latter usually start with nationwide calling and then tack on another charge for worldwide calling or even separate charges for different countries.
Similar to Ooma's residential service (below), AXvoice deploys its home VoIP with the help of an appliance, appropriately called the AXvoice Device, which sits between your home's phones and your Internet router. This device not only serves as a bridge between your old phones and the new VoIP service it also enables many of the advanced features that straight POTS bridges often don't address.
Nextiva also provides a number of helpful features for businesses working from home. For starters, there’s the Nextiva app, which lets you use your business phone number to make calls remotely from your desktop or mobile devices. Nextiva’s team collaboration tool, Cospace, also lets your team collaborate via video chat, so you can keep everyone one the same page.

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.


Vonage is probably one of the most well-known PBX providers on the market—and for good reason. Vonage phone service is easily scalable, so it can keep up with your business as it grows while maintaining affordable pricing. Vonage also offers integrations with everything from Salesforce to Slack. So if your business outgrows your current customer relationship management tools, you can switch without having to worry about whether your VoIP communications service offers integration with your new CRM.

Such emergency services are provided by VoIP vendors in the United States by a system called Enhanced 911 (E911), based on the Wireless Communications and Public Safety Act of 1999. The VoIP E911 emergency-calling system associates a physical address with the calling party's telephone number. All VoIP providers that provide access to the public switched telephone network are required to implement E911,[34] a service for which the subscriber may be charged. "VoIP providers may not allow customers to "opt-out" of 911 service."[34]


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.
The EXP40 Expansion Module for the SIP-T46S, SIP-T46G, SIP-T48S, and SIP-T48G, expanding the functional capability of your sip phone. It features a large graphic LCD. Two pages of 20 flexible buttons are shown and can be program up to 40 various features. The productivity-enhancing features include BLF/BLA, speed dialing, call forward, transfer, park, and pickup.
In the case of a private VoIP system, the primary telephony system itself is located within the private infrastructure of the end user organisation. Usually, the system will be deployed on-premises at a site within the direct control of the organisation. This can provide numerous benefits in terms of QoS control (see below), cost scalability, and ensuring privacy and security of communications traffic. However, the responsibility for ensuring that the VoIP system remains performant and resilient is predominantly vested in the end user organisation. This is not the case with a Hosted VoIP solution.
In South Korea, only providers registered with the government are authorized to offer VoIP services. Unlike many VoIP providers, most of whom offer flat rates, Korean VoIP services are generally metered and charged at rates similar to terrestrial calling. Foreign VoIP providers encounter high barriers to government registration. This issue came to a head in 2006 when Internet service providers providing personal Internet services by contract to United States Forces Korea members residing on USFK bases threatened to block off access to VoIP services used by USFK members as an economical way to keep in contact with their families in the United States, on the grounds that the service members' VoIP providers were not registered. A compromise was reached between USFK and Korean telecommunications officials in January 2007, wherein USFK service members arriving in Korea before June 1, 2007, and subscribing to the ISP services provided on base may continue to use their US-based VoIP subscription, but later arrivals must use a Korean-based VoIP provider, which by contract will offer pricing similar to the flat rates offered by US VoIP providers.[63]
A key attraction of VoIP is that it gives these systems the flexibility to work in a wide variety of environments ranging from analog desk phones to softphones piggy-backing on a cell phone. These systems can often also integrate all or part of their softphone clients into other back-office applications, like your customer relationship management (CRM) or help desk platforms. Simply picture the standard interface of such an app that suddenly sports a dial pad and some function buttons as a pop-up screen and you'll have a very basic idea of how some of this works. In addition, these cloud based systems can have a variety of phone numbers in global locations, so that your customers can have free access to your phone at little or no charge.  
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