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Showing 1 - 20 of 88 products
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Showing 1 - 20 of 88 products

Solgari

Solgari Cloud PBX is a customizable scalable PBX solution for businesses of all sizes. Solgari will plan, implement, adapt and manage the system for users. Security is provided in the form of voice traffic encryption....Read more

5.00 (1 reviews)

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Nextiva

Nextiva is a platform that brings communications together with business applications, intelligence, and automation. This helps businesses communicate and build deeper connections with their customers. The platform brings all ...Read more

4.16 (186 reviews)

14 recommendations

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Comm-unity

Comm-unity by NetFortris (formerly Fonality) is a cloud-based communication and collaboration business phone system that caters to all business sizes. Comm-unity scales easily as your business grows, always works when you need it,...Read more

3.37 (15 reviews)

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Answer360

Answer360 puts big business telephony applications in reach for small to mid-sized companies. Their applications and features are fully scalable and can be deployed on-premise or as a web-based system. ...Read more

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AVOXI

AVOXI Genius is a cloud-based call center solution that helps small to large enterprises streamline customer service operations and manage business communications. It comes with a centralized dashboard, which enables users to trac...Read more

4.74 (39 reviews)

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Convoso

Since 2006, Market Dialer has been helping businesses boost efficiency by up to 400%. Small to mid-sized businesses with a need for predictive dialing are a perfect fit for this scalable web-based phone system....Read more

4.50 (32 reviews)

1 recommendations

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Vonage Business Communications

Vonage Business Solutions is a cloud-based communications solution suitable for small and midsize companies. The solution offers a business phone system that enables businesses to connect their VoIP phone system to internet-enable...Read more

4.06 (239 reviews)

11 recommendations

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UNIVERGE 3C

UNIVERGE 3C is a flexible software-based IP-PBX. In addition to features such as auto attendants and call recording, it offers advanced unified communications capabilities so that users can harness multiple modes of communication....Read more

4.00 (1 reviews)

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MiVoice Business

"Mitel MiVoice offers a range of unified communications (UC) platforms designed for both small business and large enterprise needs. MiVoice offers virtualization options and supports both cloud-based and on-premise deployment. ...Read more

0.00 (3 reviews)

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XMission Hosted PBX

XMission Hosted PBX is a cloud-based business phone system that offers SIP trunking services for businesses seeking a single-vendor VoIP solution. It features auto attendants and hunt groups and integrates with Microsoft Outlook....Read more

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Software pricing tips

Read our SIP Trunking Providers Buyers Guide

Subscription models

  • Per employee/per month: This model allows you to pay a monthly fee for each of your employees.
  • Per user/per month: Users pay a monthly fee for users—normally administrative users—rather than all employees.

Perpetual license

  • This involves paying an upfront sum for the license to own the software and use it indefinitely.
  • This is the more traditional model and is most common with on-premise applications and with larger businesses.

Rated best value for money

TelePacific Hosted PBX

TelePacific Hosted PBX is a cloud-based phone system that also offers SIP trunking and Internet service with a variety of connectivity options. In addition to standard PBX features, TelePacific also features self-service portals....Read more

0.00 (1 reviews)

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Switchvox Phone System

Digium business phone systems deliver a comprehensive set of unified communications known as Switchvox for small to midsize businesses. All Switchvox features are included for each user licensed on the system....Read more

4.00 (28 reviews)

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BroadVoice Cloud PBX

BroadVoice b-Hive helps call and collaborate from anywhere with a single cloud communication solution that unifies business phones, video conferencing, texting and collaboration under a single phone number. Untether your team fro...Read more

4.55 (29 reviews)

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OnSIP

OnSIP Hosted PBX is a cloud-based phone system. that offers custom integrations in addition to standard PBX features, such as auto attendants and voicemail-to-email. A browser-based unified communications client is also available....Read more

4.63 (8 reviews)

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AirePBX

AirePBX is a cloud-based phone system for businesses with up to 1,000 employees. On-site installation is free. AireSpring offers SIP trunking and controls quality by providing a managed enterprise session border controller. ...Read more

5.00 (1 reviews)

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VirtualPBX

VirtualPBX is a cloud-based phone solution that caters to all-sized businesses. VirtualPBX enables companies to streamline and improve communications with features such as unlimited minutes, video conferencing, business SMS, auto-...Read more

4.85 (23 reviews)

6 recommendations

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FortiVoice

FortiVoice, an on-premise VoIP solution from Fortinet, allows users to route and screen calls and supports backup connections to the public switched telephone network, as well as a SIP trunking service for single vendors....Read more

0.00 (2 reviews)

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VoiceMaxx CE

VoiceMaxx CE (Cisco Edition) by West IP Communications is a cloud-based enterprise PBX solution. Key features include inbound and outbound calling capability, call control functionalities, personal conferencing and 'Mobile Connect...Read more

3.00 (1 reviews)

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Mobex Hosted PBX

Mobex Hosted PBX is a Web-based phone system for businesses with under 100 employees. Mobex also offers SIP trunking for a single-provider solution. Service is priced according to a per line (i.e., call path) or per user basis....Read more

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CloudCall

CloudCall is a cloud-based telecommunications and business VoIP solution. Key features include power dialer, call reports, real-time dashboards and automatic call distribution (ACD). The cloudcall portal helps in managing org...Read more

4.11 (36 reviews)

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Popular SIP Trunking Providers Comparisons

Buyers Guide

Last Updated: March 11, 2022

SIP trunking is a network service that allows businesses to connect VoIP phone systems to the traditional phone network. While this service is generally included with “per-user” licenses for cloud-based phone systems, if you have an on-premise system you’ll most likely need a SIP provider to connect calls with it.

We’ll explain what SIP trunking is, why you need it, and the primary considerations that you should factor in when deciding on a provider.

Here's what we'll cover:

What Is the Session Initiation Protocol (SIP)?
What Is a SIP Trunk
Benefits of SIP Trunking
Features of SIP Trunking Service
Important Considerations for Buyers

What Is the Session Initiation Protocol (SIP)?

Imagine the Internet as a vast network of roads and highways. On it are many types of vehicles, delivering various-sized packages (or packets, to use the technical term) containing a variety of information at a wide range of speeds. Most Internet users only ever see the contents of the vehicles traveling on the roads.

But like real roadways, the Internet has many layers below the surface. These lower layers support—and determine the quality of—the layers above them. Each layer has its own specific set of languages used to communicate within that layer. These languages are called “protocols.”

One of the lowest layers supporting the Internet is called the link layer. Within the link layer, link layer protocols organize groups of local connections into large networks. At the top, just under the surface, is the application layer. The application layer determines the quality of the “road surface” directly above it. SIP is a protocol that operates within the application layer.

Different application layer protocols are used to create different surfaces. The Internet has a wide variety of road surfaces, some favoring certain types of traffic over others: Compare a heavily loaded truck slowly climbing the rough road surface of a hill to a sports car zipping down smooth concrete. Some surfaces work better for certain purposes.

VoIP—phone conversations over the Internet—are one very particular type of traffic. They require audio to be delivered consistently with minimal delay. SIP is an application layer protocol designed to provide a very certain type of road surface for this special traffic. SIP initiates the sessions (or connections) that prepare the network to best meet the specific needs of a real-time audio connection over the Internet. 

We offer a fuller explanation in our article on the SIP protocol.

What Is a SIP Trunk?

We’ve mentioned that SIP trunking is a network service. It’s necessary because VoIP calls travel over the internet rather than the traditional phone network. This means that you need some way to connect calls between the internet and the traditional phone network, as otherwise you’d only be able to call other users with VoIP.

SIP trunking is the solution to this problem.

A SIP trunk isn’t a phone “line.” Instead, you connect to your SIP provider’s network using your internet connection. Your SIP provider utilizes specialized technologies to create a bridge between the internet and the traditional phone network, thereby connecting calls between these networks.

In some cases, you can get SIP trunking from the same company that provides your internet service, but in other cases you may need to use separate providers for SIP trunking service and internet service.

If you don’t have SIP trunking, you won’t be able to do much with a business VoIP phone system aside from admiring the server hardware. And while the traditional phone network is dying in the United States, it’s alive and well across the globe, so the need for SIP trunking isn’t going to disappear anytime soon.

Benefits of SIP Trunking

SIP trunking can cut costs in the following ways:

Lower trunking costs. Combined voice and data connections have traditionally been provided by telecoms in the form of Integrated Services Digital Network (ISDN) lines, also known as trunks. ISDN trunks come with fixed quantities of lines per trunk (for example, T1 trunks have 23 lines each). If a business needs even one additional line, it must purchase another entire trunk—meaning businesses often pay for unused capacity. SIP trunks are comprised of bandwidth, a flexible commodity, and their capacity can be increased on the fly.

Lower equipment expenses. Offices without SIP trunks use media gateways to translate between the analog PSTN and the office’s internal digital traffic. Offices using SIP trunks don’t need this expensive piece of equipment because their traffic bypasses the PSTN. A SIP trunk also makes it more practical for an office to use a cloud-based phone system rather than purchasing and maintaining an in-office hardware version.

Lower calling charges. Traditionally, and under many existing calling plans, charges are calculated based on the physical length of the PSTN line required to complete a call. Calls made via SIP trunks bypass most of the PSTN and so avoid many long-distance charges.

SIP providers also frequently offer better rates on international calls than traditional phone service providers, and most importantly, intra-office calls and calls between branch offices are frequently free when connected via SIP trunking.

SIP trunking also has a number of technological advantages:

More communications options. A SIP trunk extends, in a virtual sense, an office’s internal network to the outside world—letting remote offices, mobile employees and customers worldwide interact as if they were in the same building. Click-to-call website options for customers, application sharing and simple call transferring for work-at-home or abroad employees, for example, can all be done more easily with SIP trunks.

Meanwhile, SIP client apps can facilitate communication via a mobile device over an Internet connection, with capabilities such as voicemail, SMS messaging and more.

Features of SIP Trunking Service

The following table shows some common features of SIP trunking service:

Bursting Traditionally, if you needed more calling capacity on your phone lines, your provider took a month or longer to deliver it. SIP providers, on the other hand, can scale capacity up and down in as little as 24 hours, a vital cost-saving feature for businesses with fluctuating call volume.
Port sharing If you have multiple sites, and one site maxes out its number of simultaneous calls, you can connect calls via open ports at one of your other sites. Again, this is a vital cost-saver for call centers.
Disaster recovery In case of a service outage at one of your sites, your SIP provider can forward calls made to critical phone numbers.
911 and E.911 support Your SIP provider can support 911 calls by providing location information with the call. Without E.911 support, VoIP isn’t compatible with emergency services.
MPLS support Multi-protocol label switching is a networking technology that allows information to be routed within a network using path labels rather than the network protocols we discussed above. This offers performance, reliability and security benefits, and some businesses prefer to have SIP trunks delivered over MPLS. You’ll need to make sure your provider offers both MPLS and SIP trunking services, however.

Important Considerations for Buyers

Phone system deployment type. Whether you have an on-premise or cloud-based system is the most important factor affecting your approach to SIP trunking. Businesses with cloud systems may not even need a separate SIP provider.

In most cases, SIP trunking is included with “unlimited” user licenses for cloud systems. The vendor generally doesn’t even mention that SIP trunking is included, given the complex nature of the service. Other cloud vendors provide “metered” SIP trunking - i.e., SIP trunking service priced using per-minute rates. If you have an on-premise phone system, however, you’ll need to search for a SIP provider, as generally vendors of on-premise systems don’t offer SIP trunking.

Phone system brand. Different phone system vendors have implemented the SIP protocol in their systems in different ways. This means that not all SIP providers will be compatible with your specific brand of phone system. Check with your phone system vendor, as many list the SIP providers that their systems support. You also need to ask your SIP provider about support for specific features and devices such as FAX machines.

Connection type. A SIP trunk can be provided over most any high-speed Internet connection. The cheapest option uses an existing broadband Internet connection from a standard Internet service provider (ISP), and simply has the ITSP service share it. Call quality and capacity may be reduced because both data and voice are sharing the connection. A more expensive—but better—option is to lease a line from an ITSP and dedicate it solely to your SIP traffic. Giving your SIP traffic its own line helps improve call quality and reliability. Not all SIP providers offer internet service, but many partner with ISPs.

Quality of service and service level agreements. Quality of Service (QoS) and Service Level Agreements (SLAs) are common components of the contracts businesses sign with their ITSP. The QoS agreement defines (in technical terms regarding IP traffic’s delay, jitter and packet loss) the acceptable average quality of a voice call. The SLA, on the other hand, describes exactly how much "downtime" a service provider is allowed, what constitutes downtime and how quickly network issues must be resolved.

Trial period. ITSPs recognize that it can be difficult for a business to commit to a new phone system without experiencing it firsthand. For this reason, many now offer full or limited trial periods. The trials can be adopted on a small scale to make sure everything is functioning as expected before making the switch. Make sure to test any devices such as FAX machines that are connected to the phone network as well as the actual features of your phones.

911 dialing. The FCC has mandated that all “interconnected” VoIP services provide functionality to connect 911 calls to the appropriate local emergency services authority. But not all ITSPs fall under this mandate. If a business plans to eliminate their PSTN service entirely, then this needs to be considered. Maintaining a single PSTN line for emergencies is a viable option.

Firewall and security. If not properly managed, SIP trunks can expose an office network to external privacy and security threats. Traditionally, offices have used standard firewalls to keep out unwanted IP traffic, but SIP traffic does not always travel smoothly through firewalls. Other security options, like Virtual Private Networks (VPNs) and session border controllers, are increasingly common.