Skype is a global Internet communications company that empowers people everywhere with free, unlimited, high-quality communication through its award-winning, innovative peer-to-peer networking software on Windows, Linux, Mac OS X, and Pocket PC platforms. Quality voice calls. Skype is available in 27 languages ??and is the fastest growing voice communication method in the world. Since its launch in August 2003, Skype has been downloaded more than 182 million times in 225 countries and regions, 59 million users have registered to use Skype's free services, and there are more than 3 million online users at the same time. Skype makes money through the top-notch services it provides, has an expanding global partner network, and has a group of developers dedicated to the development of the Skype API (Application Programming Interface). Skype Technologies is headquartered in Luxembourg, with offices in London and Estonia.

(www.skype.com)

What technology does Skype use?

It is said that Skype’s voice quality is very good and it uses P2P technology, but this P2P technology should be different from BT’s P2P technology, because to support real-time voice transmission, the requirements should be higher.

1. Adopt leading P2P technology

Currently popular IM software basically adopts the centralized Client-Server model, which requires a large number of server resources for centralized storage of information. , communication coordination, etc. P2P technology is equivalent to using each client as a server resource to play a role in the entire network.

The non-centralized P2P network is superior to the traditional Client-Server model network in some aspects. This kind of network can be expanded infinitely, and the expansion will not lead to an extension of search time and an increase in costs. It utilizes the processing power and network bandwidth of the end-user machine. The processing power of the decentralized network itself is directly proportional to this, that is, with each additional node, the processing power and bandwidth of the P2P network increase accordingly. Therefore, this P2P network technology that utilizes node resources can actually completely eliminate the fees required by the original centralized network.

P2P technology also has advantages in penetrating firewalls and NAT (Network Address Translation). Traditional centralized networks can also penetrate firewalls and NATs, but this usually adds very expensive costs. The more users there are, the more costs will increase proportionally. Therefore, service providers that provide such services can usually only provide very few server resources to each user, which greatly reduces the quality of voice calls. Skype realizes the decentralization of network resources (that is, instead of using centralized server resources, it uses the network resources of each node). The completion rate and voice quality of voice calls even exceed those of traditional telephone networks to a large extent.

From a search perspective, the technology used by Skype can be called the third generation of P2P network technology. P2P technology was first widely used by some file sharing applications, such as the very famous Napster and KaZaA. Recently, the more popular ones include BT, etc. The more famous domestic P2P software includes POCO, OP, etc. In such applications, users can share, search and download files. The P2P network technology used by these file sharing can also decentralize resources, but the network used by the file sharing P2P technology is segmented in nature, that is, when you search, you cannot search. to all nodes in the network. In order to achieve high-quality and low-cost voice calls, third-generation P2P network technology must be implemented. Skype uses Global Search Directory (GI), which represents another sense of scalable network technology. The global search directory uses a multi-layer network structure. This structure uses supernodes to realize that each node in the network can obtain the resources of all other available nodes and dynamically combine these node resources to participate in traffic distribution, Path selection, processing of tasks requiring larger bandwidth, etc., and ensuring minimum delay.

Adopt intelligent routing for data transmission to ensure voice quality. By utilizing all node resources, Skype can intelligently search for the best transmission path for each encrypted call.

You can even open multiple transmission paths in parallel and dynamically select the best path in time. This has a very obvious effect on reducing latency and enhancing voice quality.

2. Penetrate firewalls

Most Voice-over-IP applications cannot penetrate firewalls and NAT (Network Address Translation). Almost all broadband users are behind firewalls and NATs, so they cannot use VoIP applications. Skype is not a typical VoIP program, it uses P2P technology and can work behind almost any firewall or NAT.

The entry port number of most such software is specified. Skype does not specify the entry port number. Instead, it randomly selects an entry port when installing the program, which can enhance the penetration of network address translation. (NAT), because if there are several users behind NAT using the same port, NAT will degrade the voice quality.

3. Security Encryption

Skype adopts end-to-end encryption to ensure the security of information. Skype encrypts information (voice, instant messages, files) before sending it and decrypts it when it is received. Even if the data needs to be transferred through other nodes during the transmission process, it is completely impossible to be eavesdropped in the middle.

Skype uses digital signatures to ensure that user data stored in the P2P network is not tampered with. Since Skype uses P2P technology, user data is mainly stored in the P2P network and is obtained from the public network when users perform searches and other operations. This must ensure that the data stored in the public network is reliable and has not been tampered with. Skype uses digital signatures for user-related data stored in the public directory to ensure that the data cannot be tampered with.

4. Easy to use and powerful

Skype has the best voice quality to date. Many VoIP and chat tools today are not comparable to Skype. Skype has teamed up with the best acoustic scientists to create exclusive, copyrighted software that can deliver voice quality even higher than landlines. In technical terms, with a traditional phone you can only hear speech at frequencies between 300Hz and 3000Hz. Skype can hear speech at all frequencies, from the deepest to the sharpest.

High call success rate. No other Internet technology system has as high a call connection rate as Skype.

Easy to use. Today's VoIP applications are difficult to configure and nearly impossible to use for users unfamiliar with networking and computing technology. Whether in terms of software or hardware, Skype users do not need to make any final settings. Usually, they can log in immediately and start voice calls as long as they register an account.

Absolutely safe way to call. As mentioned above, all communications are encrypted end-to-end and therefore completely secure.

Multi-party voice calls. Skype is the first among similar software to provide free multi-party voice calls, using a mixing method, which is easy to operate, has good sound quality, and saves network and machine resources as much as possible.

5. Save resources as much as possible

Skype has lower network bandwidth requirements than similar products. Skype can also use voice when dialing up the Internet through a Modem of 33.6Kbps or above. call. Skype can automatically select the best encoding method based on the connection status of both parties. The average bandwidth occupied during a voice call is about 3-16KB/S. The actual bandwidth occupied will vary depending on the bandwidth of the other party, network conditions, and CPU performance. When idle, it only requires about 0-0.5 k/s bandwidth, which is mainly used to update friends' online information. Specific bandwidth conditions may be affected by many factors.

When using Skype to transfer files, if the two parties cannot connect directly, they will be transferred through the resources of other users. Ordinary similar software usually relays through the server when it cannot be directly connected. Skype does not use the resources of the server, but relays through other user machines in the network. In order not to occupy too much resources of users doing transit, the speed is limited to less than 500K/S.

6. Cross-platform

Currently, most IM software can only run on the Windows platform. Even if there are separately developed versions for other platforms, their functions are often very weak, such as being limited to text information exchange. Skype currently has versions that are fully applicable to Windows operating systems, Pocket PC, Mac OS and Linux operating systems. Data transmission such as voice calls and file exchange can be carried out across platforms. The underlying technology used by Skype ensures that it can be easily transplanted to different terminal devices and is more adaptable to the development of terminal devices and communication technologies.