computer science

Kamailio

Kamailio is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Kamailio rather than just read about it. In short: Kamailio, formerly OpenSER (and sharing some common history with SIP Express Router (SER)), is a SIP server licensed under the GPL-2.0-or-later license. It can be configured to act as a SIP registrar, proxy or redirect server, and features presence support, RADIUS / syslog accounting and authorization, XML-RPC and JSON-RPC-based remote control, SQL and NoSQL backends, IMS / VoLTE extensions and others.

Key takeaways

Kamailio belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kamailio to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kamailio from memory before moving on to harder problems.

Reference excerpt

Kamailio, formerly OpenSER (and sharing some common history with SIP Express Router (SER)), is a SIP server licensed under the GPL-2.0-or-later license. It can be configured to act as a SIP registrar, proxy or redirect server, and features presence support, RADIUS / syslog accounting and authorization, XML-RPC and JSON-RPC-based remote control, SQL and NoSQL backends, IMS / VoLTE extensions and others.

Kamailio is a Hawaiian word. Kama'ilio means talk, to converse. "It was chosen for its special flavour."

Features Kamailio is written in pure C with architecture-specific optimizations; it can be configured for many scenarios including small-office use, enterprise PBX replacements and carrier services—it is SIP signaling server—a proxy—aiming to be used for large real-time communication services. Features include:

SIP telephony system SIP load balancer SIP security firewall Least cost routing engine IMS/VoLTE platform Instant messaging and presence services SIP IPv4-IPv6 gateway MSRP relay SIP-WebRTC gateway

Usage Kamailio is used by large Internet Service Providers to provide public telephony service. The largest public announced deployment with several million of users is in operation at the German ISP 1&1. Another large deployment is in operation at the provider sipgate.

Forks

OpenSIPS OpenSIPS, a fork of SER which has diverged—deciding to "go their own way" from the SER and OpenSER codebases—is a free software implementation of SIP for voice over IP (VoIP) that can be used to handle voice, text and video communication. OpenSIPS is intended for installations serving thousands of calls and is IETF RFC 3261 compliant. The software was recognized by Google in 2017 with their Open Source Peer Bonus award.

History Kamailio's roots go back to 2001, when the first line of SIP Express Router (SER) was written; at the time, the working group published results at iptel.org—in September 2002 the code itself was published under the GPL. The first fork of SER came in 2005—OpenSER—which would later merge back into the code that would become Kamailio. The codebases of SER and OpenSER (by then known as Kamailio) converged in December 2012, and it was decided to continue to use Kamailio as the main name of the project, which remains open source. During the first years of development, serweb—a web-based user provisioning—was available.

Timeline

2001

SIP Express Router (SER) is initially developed by the Fraunhofer Institute for Open Communication Systems (FOKUS) 2002

First third-party contribution (ENUM module) September

Code is GPL'd and first published 2003

Adoption by the general public begins; additional free and open source code is contributed by independent third parties 2004

Part of the FOKUS team moves, with the SER copyrights, to the newly created company iptel.org Two of the five SER core developers and one main contributor start a new free and open source software project named OpenSER. 2005

The company IPtel.org is bought by TEKELEC, and is responsible for the TEKELEC session router and CSCF. 2007

May 12

SER 2.0 RC-1 (Ottendorf) is made available 2008

August

OpenSER is renamed Kamailio to avoid conflict with similar trademarks November 4

Kamailio developers sketch and announce a plan to team up with the SER developers to create the future sip-router project 2013

FOKUS and the Kamailio community organize the first iteration of the annual 'Kamailio World' conference in Berlin, Germany.

References

External links

Kamailio Homepage

Illustrations

Worked examples

Example 1 — a first encounter with Kamailio

Start with the simplest possible case. Write down what Kamailio claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Kamailio before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Kamailio ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Kamailio

In research: Kamailio appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Kamailio in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Kamailio is common in secondary-school and first-year university syllabi. It links to neighbouring topics Free VoIP software, Free routing software, Free server software, so understanding it makes those chapters shorter.
In everyday life: Look for Kamailio outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Kamailio in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kamailio means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Kamailio out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kamailio in simple terms?

Why does Kamailio matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Kamailio?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Kamailio.