June 13, 2018
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Are you considering starting your own VoIP business or building your own VoIP system? You’ve surely seen or heard about VoIP softswitch many times while researching. You know that it is the core to build VoIP, however, you don’t clearly understand what it is. We are here to rescue. Let’s understand what VoIP softswitch is, its types, and their differences.

What is VoIP softswitch?

The term softswitch is the combination of the words software and switchboard. VoIP softswitch is the backbone of VoIP system. It connects phone calls from one line to another, across telecom network, or Internet connection. Simply put, it enables IP-to-IP calls. Softswitches are software-based, in contrast with traditional phone calls routed by hardware. In this way, softswitches eliminate the need for any type of hardware. Most VoIP softswitches have a lot of features, which make them even more attractive and user friendly. The main goal of VoIP softswitch is to handle VoIP calls. However, you also get many more features such as call recording, monitoring, voicemail to email, call queuing, etc. You are able to make audio calls, video calls, conference calls, instant messaging, online faxing, and many other advanced features at a low price.

Types of VoIP softswitches

Usually, VoIP softswitches are subdivided into two classes: Class 4 and Class 5 softswitches. Each of them has its functionalities and features and using purposes. That’s why you should know the purpose of each VoIP softswitch and how they differ from each other to better understand which one meets your business requirements. Let’s explore them one by one.

Class 4 softswitch

The main functionality of Class 4 VoIP softswitch is to route large volume of calls over long distances at a low price. These calls can be carrier to carrier, between carriers, or local office exchanges. Class 4 softswitches are usually used in VoIP wholesale models, as it efficiently routes VoIP traffic between carriers for long separation. It transmits large volumes of voice traffic over and between different exchanges otherwise known as LATAs (local access and transport areas). This is the reason why class 4 softswitch is also called a wholesale solution. To better understand, let’s give an example of a call based on class 4 softswitch. When you are calling from a U.S. city such as Los Angeles to a Canadian city such as Toronto, the call is made through class 4 softswitch. Among most important characteristics of Class 4 softswitch are protocol and conversion, transcoding, billing, protocol support, average time of one call routing, number of concurrent calls, etc.

Class 5 softswitch

In contrast with Class 4 softswitch, Class 5 softswitch routes calls between end-users or consumbers in moderately smaller areas such as a city, town, and a small state of the same country. To put it simply, the main goal of Class 5 softswitch is to enable calling in the same city, town, or region. For example, when you make a call from Miami to Los Angeles. The most direct method is to use IP phones or phones using VoIP adapters connected with directly with softswitch. However, end users can also use VoIP services from their cell phones through mobile VoIP dialer apps or softphones. Class 5 softswitch can also deliver services for non-IP devices such as regular phones. Pinless and calling cards services are among these services, enabling end users to dial into a local Class 5 softswitch and use VoIP services. This softswitch is also called retail VoIP softswitch. It provides additional services for end-users and businesses such as IP PBX features, call center services, calling card platform, IVR functionality, local switching, etc.

Class 4 VS Class 5 VoIP softswitch

How these two can cooperate?

So, let’s make it clear. Class 4 softswitch routes calls between class 5 softswitches. It operates on provider level, in contrast with Class 5 softswitch, which operates on the end-user level. However, Class 4 and Class 5 softswitches can also work together. In order to connect international endpoints, class 5 softswitch uses class 4 softswitch. Class 5 softswitch passes its traffic through a Class 4 softswitch to make long distance calls. Class 4 softswitch transmits the call over a long distance and routes it to Class 5 softswitch connected with IP phones to give VoIP services to users.

The differences between class 4 and class 5 softswitches

Undoubtedly, both Class 4 and Class 5 softswitches are complete VoIP solutions with a wide range of VoIP features. However, they greatly differ from each other. So, let’s highlight their main differences:

Main goal:

Both route calls, but there are subtle differences. Class 5 softswitch receives calls from end users and routes them between users. Class 4 softswitch receives calls from providers and routes them between carriers. 


Class 5 softswitch comes with a wide range of features such as dial tone, IVR, other calling features. Class 4 softswitch is a simpler solution enabling long distance calls.

Service type:

Class 4 softswitch is a wholesale solution. It is a central office exchange interconnecting local exchange carrier offices for a long-distance call. Class 5 softswitch is a retail solution. It is a telephone exchange, whether at the local telephone company’s office or VoIP reseller provider serving end-users.

Main peculiarities:

The main characteristics of Class 4 softswitch are:
  • Protocol support and conversion
  • Transcoding
  • Calls per second rate
  • Average time of one call routing
  • Number of concurrent calls
  • Flexible UI (user interface)
  • Intelligent call routing
  • Billing interface, including CDR
  • Secured firewall
  • Filtered third-party routing engine
The main characteristics of Class 5 softswitch are:
  • Call authentication
  • Billing and routing
  • IVR
  • Callback
  • Analog-to-digital conversion
  • Support for Codec, Media transcoding
  • Social media usability
  • Call transfer
  • Call holding
  • Call forking


Class 5 softswitches can work with the end-user as well as retail VoIP service providers, as it provides local and long-distance services for both end-users and enterprises. On the other hand, Class 4 softswitch mainly operates with wholesale VoIP solution providers, carriers, telco operators, etc.


Class 4 softswitch can handle many calls. On the other hand, Class 5 softswitch can transfer a small number of calls.

Route area:

Class 4 softswitch is able to roue calls throughout multiple IP network. Class 5 softswitch can route the calls to the correct IP address, SIP address, or DID number of an end-user.  We see that Class 4 and Class 5 softswitches are the core of VoIP system. That’s why choosing the right one to meet your needs is essential. Stay tuned to our next post, where we will give some tips on how to choose VoIP softswitch based on their benefits.

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