computer science

Linphone

Linphone 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 Linphone rather than just read about it. In short: Linphone (contraction of Linux phone) is a free voice over IP softphone, SIP client and service. It may be used for audio and video direct calls and calls through any VoIP softswitch or IP-PBX.

Key takeaways

Linphone 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 Linphone to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Linphone from memory before moving on to harder problems.

Reference excerpt

Linphone (contraction of Linux phone) is a free voice over IP softphone, SIP client and service. It may be used for audio and video direct calls and calls through any VoIP softswitch or IP-PBX. Linphone also provides the possibility to exchange instant messages. It has a simple multilanguage interface based on Qt for GUI and can also be run as a console-mode application on Linux. Both SIP service and software could be used together, but also independently: it is possible to connect Linphone service with any SIP client (software or hardware), and to use Linphone software with any SIP service. The softphone is currently developed by Belledonne Communications in France. Linphone was initially developed for Linux but now supports many additional platforms including Microsoft Windows, macOS, and mobile phones running Windows Phone, iOS or Android. It supports ZRTP for end-to-end encrypted voice and video communication. Linphone is licensed under the GNU GPL-3.0-or-later and supports IPv6. Linphone can also be used behind network address translator (NAT), meaning it can run behind home routers. It is compatible with telephony by using an Internet telephony service provider (ITSP).

Features Linphone hosts a free SIP service on its website. The Linphone client provides access to following functionalities:

Multi-account work Registration on any SIP-service and line status management Contact list with status of other users Conference call initiation Combination of message history and call details DTMF signals sending (SIP INFO / RFC 2833) File sharing Additional plugins

Open standards support

Protocols SIP according to RFC 3261 (UDP, TCP and TLS) SIP SIMPLE NAT traversal by TURN and ICE RTP/RTCP Media-security: SRTP and ZRTP

Audio codecs Audio codec support: Speex (narrow band and wideband), G.711 (μ-law, A-law), GSM, Opus, and iLBC (through an optional plugin)

Video codecs Video codec support: MPEG-4, Theora, VP8 and H.264 (with a plugin based on x264), with resolutions from QCIF (176×144) to SVGA (800×600) provided that network bandwidth and CPU power are sufficient.

Gallery

See also Comparison of VoIP software List of SIP software Opportunistic encryption

References

External links Official website

Illustrations

Worked examples

Example 1 — a first encounter with Linphone

Start with the simplest possible case. Write down what Linphone 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 Linphone 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 Linphone 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 Linphone

In research: Linphone 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 Linphone 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: Linphone is common in secondary-school and first-year university syllabi. It links to neighbouring topics Android (operating system) software, BlackBerry software, Communication software, so understanding it makes those chapters shorter.
In everyday life: Look for Linphone 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 Linphone in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Linphone 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 Linphone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Linphone in simple terms?

Linphone (contraction of Linux phone) is a free voice over IP softphone, SIP client and service. It may be used for audio and video direct calls and calls through any VoIP softswitch or IP-PBX.

Why does Linphone 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 Linphone?

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 Linphone.