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.
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.
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 SIP-T56A is a simple-to-use smart media phone that provides an enriched HD audio experience for business professionals. This all-new smart media phone enables productivity-enhancing visual communication with the ease of a standard phone. the SIP-T56A features a seven-inch fixed multi-point touch screen, integrated Wi-Fi and Bluetooth 4.0+ EDR, and it is coupled with a built-in web browser, calendar, recorder and more, which also support the installation of third-party applications for business customization. Thanks to the DECT technology, if you want to expand your horizons for busy environments, or, share one phone system with your small team by adding multiple handsets, simply turn Yealink SIP-T56A phone to the corded-cordless phone, and it will repay you up to 4 DECT handsets in total to meet your daily demands.
VoIP calling as your home phone service is the best way to consolidate calling and networking in one convenient place, while saving a lot of money. Landlines are limited, and serve no more function than dialing out and receiving calls. Setting up your VoIP phone to forward calls to your mobile number is just one of the many ways you can stay connected, even when you’re not home. A common concern in making the transition to VoIP is that giving up your landline service will ultimately mean giving up your number in exchange for a new one. With number portability, residential VoIP providers allow you to keep your old landline number and assimilate it into your new phone service. Check with your VoIP provider to see if your particular number is eligible for porting, as they are portable in most cases.
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.
Verizon is a household name when it comes to all things calling, and its residential VoIP services don’t disappoint. You can get both unlimited or per-minute calling plans from this communications solution giant. Verizon uses advanced fiber-optic networks to deliver the most crystal-clear sound quality too. So, you’re never struggling to hear and understand what someone on the other line is saying to you.
The quality of voice transmission is characterized by several metrics that may be monitored by network elements and by the user agent hardware or software. Such metrics include network packet loss, packet jitter, packet latency (delay), post-dial delay, and echo. The metrics are determined by VoIP performance testing and monitoring.[20][21][22][23][24][25]
You know Verizon; everybody knows Verizon. It’s a mobile leader, and its ultra-fast Fios (fiber-optic internet) service is expanding rapidly—so of course it’s also in the VoIP business. Verizon has built-in  bring-your-own-device (BYOD) solutions, as well as the internet connections (both fiber-optic and DSL) to support a reliable VoIP business service. Consolidation of all your business’s telecommunication needs into a single bill could be easily accomplished with Verizon. It would be more convenient than cheap, however.
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.
The problem there is that VoIP traffic is much more sensitive to network bumps and potholes than most general office traffic. That translates to conversations breaking up or cutting out entirely, 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 small (though still there). But for medium and larger networks, these tasks can not only be complex, but also time consuming, which translates into added cost in terms of man-hours.
When you're considering a new VoIP phone system for your business, it's important to include stakeholders from all of the key parts of your business in the planning and decision making process. Yes, this especially includes the IT staff and the data security folks since your voice communications will now be data. But it also needs to include folks who will 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 really needed versus what's simply cool and new. Plus, you'll need their input to select a phone system that will actually move your business forward as well as fit into your IT environment.
An important disadvantage of the landline is that you cannot easily scale it up or down. This is why many companies with rapidly expanding or contracting business sizes prefer VoIP because it allows enterprise management to easily add, edit or even delete user rights centrally through the control panel. It is not necessary to follow the tedious processes involved if you are using a regular landline. This makes internet phone technology significantly more suitable for large business organizations.
Typically, price is one of the most important reasons people opt for residential VoIP. One of the most attractive is the "triple play" sales pitch we mentioned above made by almost every regional residential cable company and internet provider: Get your Internet, TV, and phone service all rolled into one monthly charge. Not only is that usually an attractive number, it also means a technician will hook everything up for you including your phone, and you'll probably be able to use the same phone you're using now instead of having to migrate to a VoIP phone.

Voicemail routing can take multiple forms, but they're basically rules you can apply to incoming calls that will automatically route them to voicemail without even causing a ring. For example, if calls come in with Caller ID blocked, those can be routed directly to voicemail. Or if you're simply not into talking to anyone, you can hang out a digital Do Not Disturb sign and route all calls to voicemail, perhaps until you're feeling more social or every day between the hours of 9 PM and 7 AM. 
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]

In the following time span of about two decades, various forms of packet telephony were developed and industry interest groups formed to support the new technologies. Following the termination of the ARPANET project, and expansion of the Internet for commercial traffic, IP telephony was tested and deemed infeasible for commercial use until the introduction of VocalChat in the early 1990s and then in Feb 1995 the official release of Internet Phone (or iPhone for short) commercial software by VocalTec , based on the Audio Transceiver patent by Lior Haramaty and Alon Cohen, and followed by other VoIP infrastructure components such as telephony gateways and switching servers. Soon after it became an established area of interest in commercial labs of the major IT concerns. By the late 1990s, the first softswitches became available, and new protocols, such as H.323, MGCP and the Session Initiation Protocol (SIP) gained widespread attention. In the early 2000s, the proliferation of high-bandwidth always-on Internet connections to residential dwellings and businesses, spawned an industry of Internet telephony service providers (ITSPs). The development of open-source telephony software, such as Asterisk PBX, fueled widespread interest and entrepreneurship in voice-over-IP services, applying new Internet technology paradigms, such as cloud services to telephony.
The Yealink EXP50 Color-screen Expansion Module is an ideal solution for receptionists, administrative assistants and contact center workers and give you the ability to monitor contacts and manage a large volume of calls with ease. The Yealink EXP50 Color-Screen Expansion Module for Yealink T5 Series IP phones, including SIP-T56A/T54S/T52S, is designed to expand the functional capability of your SIP phone to a whole new level. It features a large 4.3-inch color-screen LCD, giving you a vivid visual experience. In addition, it provides you with a simple user interface and advanced call handling capabilities. For example, three pages of 20 flexible button shown on the display can be programmed for up to 60 various features.
Choose the service that is appropriate for your calling needs. Residential VoIP plans are cheaper than business VoIP plans because: (1) they have fewer features and (2) residential phones are used less frequently than business phones. Don’t use a residential VoIP service for a home-based business unless you’re willing to pay overage fees or to have your VoIP service canceled. VoIP providers are serious about enforcing their Fair Use guidelines.

We recognize that not all our readers’ businesses are based in the US. So we took another pass at our content to provide more information on each provider’s international offerings. And because 8x8’s international rates on calls made from the US are so good, we bumped it up to our number five spot. Finally, we added info about Ooma’s new plan (Ooma Office Pro) to the offerings mentioned below.
While we think Grasshopper is great for small businesses, it misses out on our “Best Small-Business Phone Service” title because, compared to Ooma, Grasshopper is a little expensive. Grasshopper plans start at $26 per month, assuming you sign up for annual billing. And starting plans include only one business phone number with up to three extensions.
Although jitter is a random variable, it is the sum of several other random variables which are at least somewhat independent: the individual queuing delays of the routers along the Internet path in question. Motivated by the central limit theorem, jitter can be modeled as a gaussian random variable. This suggests continually estimating the mean delay and its standard deviation and setting the playout delay so that only packets delayed more than several standard deviations above the mean will arrive too late to be useful. In practice, the variance in latency of many Internet paths is dominated by a small number (often one) of relatively slow and congested bottleneck links. Most Internet backbone links are now so fast (e.g. 10 Gbit/s) that their delays are dominated by the transmission medium (e.g. optical fiber) and the routers driving them do not have enough buffering for queuing delays to be significant.[citation needed]
SIP networks usually have a proxy server and a SIP gateway. The proxy sever helps lighten the functional requirements of SIP endpoints. It also acts as both client and server, but it adds functionality around call routing and policy-based management. SIP gateways handle the routing and connectivity requirements for connecting SIP calls to other networks. Typically, the advanced features of the VoIP vendors we review here are largely based on the proprietary management technology they build into their proxy servers and gateways. By offering VoIP solutions where these elements of a SIP solution are hosted in the cloud, the providers reviewed here have more flexibility in building advanced features since they have more control over deployment and reliability.

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.


Voicemail routing can take multiple forms, but they're basically rules you can apply to incoming calls that will automatically route them to voicemail without even causing a ring. For example, if calls come in with Caller ID blocked, those can be routed directly to voicemail. Or if you're simply not into talking to anyone, you can hang out a digital Do Not Disturb sign and route all calls to voicemail, perhaps until you're feeling more social or every day between the hours of 9 PM and 7 AM. 

That being said, Grasshopper doesn’t offer any conferencing tools. For that, you’ll have to sign up for join.me—Grasshopper’s sister company. This service offers both video and audioconferencing, but it does cost an extra $10–$30 per month. That’s another strike against Grasshopper, since most providers in Grasshopper’s price range include conferencing features.


The products and services in this review roundup are focused on business use and because of this either provide some PBX features or serve as full-on virtual PBXes. This may mean, among other things, that they provide service to telephone sets on your employees' desks. Most also support electronic faxing in some fashion, either directly (which can be a significant challenge for some VoIP services) or by simply integrating an incoming fax with your email system. Other popular features are video conferencing and shared meeting software (so meeting attendees not only hear each other but can present presentations or documents in a shared work space).
A voice call originating in the VoIP environment also faces challenges to reach its destination if the number is routed to a mobile phone number on a traditional mobile carrier. VoIP has been identified in the past as a Least Cost Routing (LCR) system, which is based on checking the destination of each telephone call as it is made, and then sending the call via the network that will cost the customer the least. This rating is subject to some debate given the complexity of call routing created by number portability. With GSM number portability now in place, LCR providers can no longer rely on using the network root prefix to determine how to route a call. Instead, they must now determine the actual network of every number before routing the call.[citation needed]
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]
PhonePower is one of a handful of VoIP providers that actually specialize in residential VoIP rather than business VoIP. Although PhonePower has many plans, it’s best for calling within the US (including Puerto Rico) and Canada. That’s because it has possibly the cheapest prices in residential VoIP, providing you’re calling solely on local numbers. PhonePower also enables calls abroad, although there are cheaper options such as Vonage if you’re planning on making more than an hour’s worth of calls internationally each month.
The Yealink Touch-sensitive HD IP Conference Phone CP920 is comprised with the Android 5.1 operating system. With a user-centric design, it combines simplicity of use with sophistication of features, being perfect for small to medium sized conference rooms. With its crystal-clear audio quality, your conversation will sound natural and bright anywhere with well-designed CP920. The Yealink CP920 can be not only paired with your mobile staff –smartphone or PC/tablet via Bluetooth, but also is a good choice for businesses that use a public switched telephone network (PSTN) after combining with CPN10 PSTN Box. As a valuable complement for your conference room, CP920 conference phone strikes an excellent balance between ease-of-use and powerful features, giving you a simply and clearly engaging business conference experience.
Like the rest of us, you probably don't like to get hassled with unwanted phone calls when you’re at home. You can also implement “enhanced call forwarding” to reroute and block the numbers that you specify, without the caller having any idea. You also can set up your phone to block international and directory assistance calls, so they don’t bother you at home. 
VoIP Office, a leading provider of Cloud based communications, makes it affordable and easy to connect to anyone, anywhere in the world. Our communications solutions meet the needs of any type of business in any industry, from home offices to large enterprises. VOIP OFFICE is a new-generation cloud based communications provider that offers all the features of your traditional PBX along with the latest functionality enabled by the use of VoIP technology. Voip Office integrates easily with your business applications, seamlessly integrating your desktop and your office into one interconnected system.
Step 3 is all about reviews. However, as this section is about comparison we are introducing our Ratings Comparison Tool in this section. This tool allows the ability to select from a list of service providers and compare user review ratings side by side. You can also select specific rating categories for a seletion of providers and visually compare in a graphical representation.
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