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.
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]
A critical part of the discussion with your IT staff will be whether your existing data network can handle the extra load that will be placed on it by the new phone system. You'll need a network that can handle more advanced network management capabilities, including tools to fight jitter and latency as well as to provide Quality of Service (QoS) and different kinds of network segmentation, especially virtual LANs (VLANs). Only tools like these can help free up your network from too much congestion, which can cause your call quality to decrease or even crash the VoIP system entirely.  
VoIP solutions aimed at businesses have evolved into unified communications services that treat all communications—phone calls, faxes, voice mail, e-mail, web conferences, and more—as discrete units that can all be delivered via any means and to any handset, including cellphones. Two kinds of service providers are operating in this space: one set is focused on VoIP for medium to large enterprises, while another is targeting the small-to-medium business (SMB) market.[13]
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]
Multiple Numbers on Demand – Building a multifaceted business phone service with any kind of localized number or vanity number. Whether it’s business VoIP solutions for small business, enterprise, or contact center, communications is only as strong as it is dynamic, with multiple numbers, all having specific assignments to fulfill. Some business Voice Over IP phone providers will offer these additional numbers for free, or an additional small monthly fee. Explore options to find out if a provider supplies key components beyond a local number such as toll-free numbers, virtual faxing, and virtual extensions.

Our real estate investment company has 14 phone lines altogether. For a phone service, we needed a local number, good call quality, uninterrupted service, calling apps for our laptops and cell phones, and an internal messaging platform for team communication. We started out with a niche company called Sound Communications, but their call quality and app were not very good. So once we made a bit more income, we decided to switch to RingCentral. RingCentral provides great call quality and is highly recommended in the real estate investment community. They are on the pricier side—$419.88 per line per year—but I’m OK with the price because their service is worth it and the high-quality phone calls are very important to our business.
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.
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.
While it doesn't offer as many features as its business-class version, residential VoIP is still overwhelmingly attractive when compared to standard phone service; firstly because of its much lower overall price tag and second because it simply offers more features than an old fashioned long line. You can keep your current number, suffer zero restrictions when it comes to 911 or long-distance calling, drop your monthly price to a low fixed number, and take advantage of VoIP-only features like smart call routing, virtual numbers, and more.
Setting up a residential VoIP system can mean big savings on your phone bill, especially if you make a large number of long distance and international calls. In addition, these systems are mobile-optimized, and provide a wealth of features that may just change the way you think of your home phone service. Take a look at the features you need and the budget you can handle, and make the decision that’s right for you.
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]
While the exact features offered in any particular UCaaS solution can change radically from vendor to vendor, most include options for video conferencing, shared meeting and document collaboration tools, integrated faxing, mobile VoIP integration, and device-independent softphone clients. All of these options let customers look at communications in a whole new way, namely, in an a menu-style manner where they can implement only those features their business needs and then access them any time they want and in any combination. This new approach to business communications has been growing steadily among customers over the past few years as recent research from Statista bears out.  
For a VoIP system to work, it needs a means of routing calls between users or to the outside world. In a cloud based system, a virtual PBX does that job. What that means to you is that the provider is running a large PBX operation in a data center somewhere, and slicing off a little of it to dedicate to your organization in exchange for your money. You're essentially sharing a large PBX with that provider's other customers, but because these companies use multi-tenant segmentation, your PBX will appear dedicated to you. This engine will take care of routing calls on your VoIP network.
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.
Operators of "Interconnected" VoIP (fully connected to the PSTN) are mandated to provide Enhanced 911 service without special request, provide for customer location updates, clearly disclose any limitations on their E-911 functionality to their consumers, obtain affirmative acknowledgements of these disclosures from all consumers,[65] and 'may not allow their customers to “opt-out” of 911 service.'[66] VoIP operators also receive the benefit of certain US telecommunications regulations, including an entitlement to interconnection and exchange of traffic with incumbent local exchange carriers via wholesale carriers. Providers of "nomadic" VoIP service—those who are unable to determine the location of their users—are exempt from state telecommunications regulation.[67]
E.164 is a global FGFnumbering standard for both the PSTN and PLMN. Most VoIP implementations support E.164 to allow calls to be routed to and from VoIP subscribers and the PSTN/PLMN.[27] VoIP implementations can also allow other identification techniques to be used. For example, Skype allows subscribers to choose "Skype names"[28] (usernames) whereas SIP implementations can use URIs[29] similar to email addresses. Often VoIP implementations employ methods of translating non-E.164 identifiers to E.164 numbers and vice versa, such as the Skype-In service provided by Skype[30] and the ENUM service in IMS and SIP.[31]
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 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.

It is much cheaper than a regular landline - most providers offer unlimited calling plans (including long distance) in the USA and Canada for under $10 per month. There are also some great promotional deals available such as 2 year specials that cost around $6 per month (includes all your calling). Comparing this to a regular PSTN (landline) phone service that can cost in the region of $60 per month can result in savings of over $500 per year for many home phone users. If you also regularly call International numbers you can save even more, with rates typically starting from around 1 to 2 cents per minute to many countries.