Kamailio vs. OpenSIPS: Differences & How to Choose One

Understanding Kamailio and OpenSIPS

Before diving into the differences between Kamailio vs. OpenSIPS, we’d like to give you a quick overview of these two SIP servers.

Kamailio

Kamailio started in 2001. It was first known as OpenSER, a SIP Express Router (SER). But over time, it has evolved and changed its name to Kamailio. This platform is popular in the VoIP community for its high performance, scalability, and flexibility.

With these benefits, Kamailio is capable of processing thousands of calls per second. This makes it ideal for large-scale deployments. Further, Kamailio also ensures reliable VoIP communication even under heavy loads. As such, the server can perform effectively and efficiently when it’s scaled up to support a large number of operations, users, and calls, like in a big company or a widespread network.

Kamailio also enables a wide range of custom configurations. Accordingly, you can tailor its settings and features to fit your specific requirements. This makes the server adaptable to many use cases.

So, how does Kamailio work? This platform works by managing and routing SIP messages. As such, it processes the signaling required to set up, monitor, and end VoIP calls. When you make a call, for example, Kamailio handles the request and directs it to the correct destination. Moreover, Kamailio manages registration, authentication, and other crucial functions.

OpenSIPS

OpenSIPS was created in 2008 by taking the original codebase of the SER project and developing it separately. The goal was to craft a more feature-rich and flexible SIP server.

OpenSIPS stands out for its modular architecture. It allows you to customize and expand the platform easily. For this reason, you can ensure a more efficient operation while scaling the server to fit your business needs.

OpenSIPS also supports multiple features out of the box. This involves advanced routing, load balancing, and security features. Like Kamailio, OpenSIPS is also highly scalable and well-suited for small and large VoIP systems. This makes it a favorite for many VoIP service providers.

OpenSIPS works in a similar way to Kamailio. Particularly, it handles SIP signaling for VoIP calls, monitors user registrations, and more. Further, you can load only the features you need to keep the server smoothly functioning.

5 Key Differences Between Kamailio vs. OpenSIPS

5 key differences betwen Kamailio vs. OpenSIPS

As the VoIP market continues to expand, the demand for VoIP servers is increasing accordingly. In particular, the US-based VoIP revenue is projected to grow at a yearly growth rate of 10.4% from 2022 to 2032. The growing adoption of VoIP is also driving a higher need for robust and scalable SIP servers, such as Kamailio and OpenSIPS, to support the rising volume of communication over the Internet.

Each SIP server has its own strengths and weaknesses. Here are the five core differences between Kamailio vs. OpenSIPS:

Performance

Kamailio stands out for its impressive performance. It can handle a high volume of calls at the same time. This makes it suitable for large deployments and busy networks. Kamailio’s architecture is also optimized for speed and efficiency. It handles SIP messages quickly. This ensures minimal delay in call setup and management.

OpenSIPS, on the other hand, also delivers strong performance. It supports thousands of concurrent calls with ease. Its modular design contributes to its efficiency. As we mentioned, you can load only the necessary modules to optimize performance. Further, OpenSIPS is developed to scale effortlessly, making it a good choice for growing networks. It also handles SIP traffic efficiently. This maintains the high quality and responsiveness of your VoIP system.

Based on our above analysis, it’s easy to see that both Kamailio and OpenSIPS have high performance. Kamilio is praised for its speed and stability, especially in high-traffic environments. Meanwhile, OpenSIPS is beneficial for diverse and expanding needs.

To choose between them, you should establish more specific performance requirements. For example, your company already operates a large call center with thousands of agents making and receiving calls concurrently. So, you need a SIP server that can process a very high volume of traffic efficiently. In this case, choose Kamailio due to its proven ability to manage heavy loads with minimal latency.

If your company operates a smaller but rapidly growing VoIP service that needs frequent updates and custom features, choose OpenSIPS. It’s because this server allows you to add and remove features easily. This makes it adaptable to your changing needs.

Features & Architecture

Kamailio is packed with various features. It has advanced routing capabilities, such as complex call handling and custom logic. Kamalio also includes built-in support for different authentication methods and security features. Its configuration is highly flexible, allowing for detailed customization to meet specific needs. The server also offers comprehensive logging and monitoring tools to track your system performance and troubleshoot issues.

OpenSIPS also provides a rich suite of features. It involves a modular architecture that lets you choose and configure only the components they need. This modularity allows for advanced functionalities like load balancing, call routing, and multi-tenancy. OpenSIPS also supports a wide range of VoIP protocols and standards. This ensures compatibility with many systems. Its scripting capabilities enable extensive customization and integration with other services.

So, we can see both Kamailio and OpenSIPS provide a robust set of features. Kamailio stands out with detailed customization and security options. This makes it ideal for complex setups. OpenSIPS, meanwhile, excels in its modular approach and versatility. This allows you to tailor the server to specific requirements, as we already mentioned.

The choice between them depends on whether you need extensive built-in features and security (Kamailio) or flexible, modular functionality (OpenSIPS).

Programming Language

Kamailio uses a native scripting language. This is a domain-specific language (DSL) developed specifically for configuring the Kamailio server. This language is often used in `kamailio.cfg`, a centralized configuration file, to define routing logic, load modules, and set various parameters. Initially created in 2001-2002, this DSL is unique to Kamailio and isn’t based on other programming languages.

Further, Kamailio uses the KEMI framework that offers flexibility to use different external scripting languages for configuration. KEMI here stands for Kamailio Embedded Interface. Accordingly, you can write Kamailio scripts using popular languages like Lua, Python, or Ruby. KEMI also provides an interface for integrating these languages into Kamailio’s configuration process. This gives extra flexibility beyond the native DSL. For this reason, Kamailio is highly flexible and accessible to developers familiar with these languages.

OpenSIPS itself, on the other hand, is written in C to ensure high performance and efficiency. However, it uses its own proprietary scripting language for configuring and defining routing logic within OpenSIPS. This scripting language is developed for SIP routing and message handling.

Compared to using popular programming languages in Kamailio, this scripting language of OpenSIPS has a steeper learning curve. However, it has a syntax that is similar to C. This helps developers quickly master this language.

Further, this scripting language, together with OpenSIPS’s modular architecture, provides high-performance and fine-grained control over SIP processing. This makes OpenSIPS easily adopted in plenty of scenarios. Only by uploading your needed modules and using the scripting language to build on top of them, you can customize the server with ease.

Configuration

Configuration refers to the process of installing and tailoring a SIP server to handle SIP messages based on your specific needs. This includes defining how the server will process incoming and outgoing SIP requests, how it interacts with other components, and how it manages different features.

OpenSIPS has its own configuration file (`opensips.cfg`). This file is where you can loaf and configure modules, define routing logic, and establish parameters. It also offers detailed and precise control over SIP message handling. While the learning curve might be steeper, OpenSIPS’s configuration enables high performance and fine-tuned control.

In particular, OpenSIPS uses a modular configuration approach. This involves configuring each module independently, which can be reflected in separate configuration files or sections. This enables more flexible and efficient customization of modules to fit your needs.

Kamailio, meanwhile, uses a central configuration file called `kamailio.cfg`. This is where you define all settings. This can be clarifying which modules to load and setting parameters for each module. The configuration file also involves routing logic, which specifies how to process and forward SIP requests. Kamailio’s configuration is very flexible. It allows you to write code within the configuration file using embedded languages (e.g., KEMI with Lua) to build, extend, or modify modules.

Like OpenSIPS, Kamailio also uses modular architecture. Accordingly, if a module for a desired functionality already exists in these SIP servers, you can integrate it into these servers without developing it from scratch. However, its configuration is mainly centralized in a single or a few configuration files. Kamailio’s modules, hence, require a more detailed setup. This might involve specifying parameters in the centralized configuration file and ensuring modules interact correctly.

Use Cases

Both Kamailio and OpenSIPS are powerful and versatile SIP servers. Yet they excel in different scenarios.

First, Kamailio is ideal for large-scale deployments. It handles high call volumes well. You can use Kamailio for load balancing, security, and NAT traversal. It’s also great for complex routing scenarios and flexible for custom solutions. Therefore, various organizations choose Kamailio to manage large VoIP networks.

OpenSIPS, meanwhile, is known for modularity and flexibility. It’s perfect for medium to large VoIP networks. Various VoIP service providers often use OpenSIPS to address SIP signaling and media processing efficiently. OpenSIPS is also a good option for implementing custom VoIP services as its modules cover routing, presence, and more. Many companies now leverage OpenSIPS as well to create scalable VoIP platforms, call centers, and IP-PBX systems.

How to Choose the Right SIP Server

How to choose the right server: Kamailio vs. OpenSIPS

You’ve understood the core differences between Kamailio vs. OpenSIPS. Both these SIP servers are scalable and highly appreciated for their performance, features, and configuration. Importantly, they’re open-source. This means you don’t need to pay anything to download and use these SIP servers, except for costs associated with hardware or software to use them. So, which one should you choose? Here, in this final section, we’ll give you a detailed 5-step guide to choose the right one for your business:

Step 1: Know Your Needs

First, clarify your specific requirements. What do you want to achieve with a SIP server? Are you focusing on high volume or a small, niche use? What kind of traffic will your server handle? Ask these questions to pinpoint the features you need. This might include scalability, security, or integration capabilities. Once you’ve comprehended your needs, you can set a solid foundation for your decision.

Step 2: Understand & Compare Kamailio va. OpenSIPS

Next, you should find more materials to better understand the two main candidates: Kamailio vs. OpenSIPS. Accordingly, you can visit their official documentation pages, community forums, mailing lists, webinars, and blogs. Then, compare different factors like their features, performance metrics, support, and ease of use. This comparison will help you assess their pros and cons, and more importantly, how they align with your specific needs.

Step 3: Consider Your Team

Never ignore your team’s expertise, experience, and resources when choosing a SIP server. Using a server that doesn’t fit your team can waste much time and effort to create a desired VoIP phone system. So, if your team is adept at complex configurations and familiar with OpenSIPS’s proprietary scripting language, pick this SIP server. In case they prefer a more straightforward setup and diverse languages, choose Kamailio.

Further, you should consider whether the server provider offers training and available support. Assessing the server’s learning curve also helps you better understand how long it takes for your team to get accustomed to and even master the server.

Step 4: Ask for Recommendations

Reach out to other experts in your industry about SIP servers. You can ask for recommendations from colleagues, online forums, or industry groups. Real-world experiences can give you valuable insights into how each server performs and what challenges others have faced.

Step 5: Try Before Use

Finally, test both servers in a pilot environment. You can set up trials to see how each server performs in real-world scenarios. Then, evaluate their Easter integration and manageability. This hands-on approach will provide evaluations beyond theoretical comparisons. It then helps you make an informed decision.

Conclusion

After this article, we expect you can better understand two scalable and versatile SIP servers: Kamailio vs. OpenSIPS. Also, you can distinguish them in terms of performance, features, configuration, programming languages, and use cases. Following our 5-step guide and considering your specific requirements, you can choose the right SIP server for your business. Subscribe to our blog to get more information about SIP servers!