ICQ system was originally created for communication with a personal computer.
However, with increasing availability of mobile phones with Internet access, programmers began to invent ways to use this system with them.
Initially, all applications for this purpose were informal, but then there were also the official.
At a time when ICQ belonged to AOL, the contractbetween the company and the user had not allowed the use of alternative clients, and officials were only for computers running Mac OS and Windows. But in practice for the use of alternative programs no one was punished. Those were created as well as for Mac OS and Windows, and OS, which was not yet official, for example, Linux. A software solution for mobile phones did not exist. WAP-browsers have already embedded in many of them, but the ability to run Java-based applications was still not all. Thus it was created a site called TJAT. It worked like this: run an alternate client to the server, and a user with a phone with a WAP-browser sign up on the web interface, introduced a number and password, and then was able to send and receive messages. The server was acting as a kind of bridge to interact with the ICQ server to "understand" his "language", and with a WAP-browser - to "understand" it. Once the server has been compromised, and the attackers gained access to a number of passwords. But by the time he was irrelevant to most users.
It was connected with the fact that soon gotdistribution of phones with the ability to run Java-based applications. It is allowed to create ICQ-client directly to mobile phones, without requiring server conditions "translator". Programmers have created several alternative clients, the most famous of which was JIMM. In terms of communication protocol, he imitated the official client, so the ICQ server willingly cooperated with him. Then AOL announced unofficial clients, including JIMM, a silent war. The protocol made changes that reflected in the official client, but the authors of informal did not immediately have time to decipher these changes and reflect in their designs. After several attempts at AOL gave up, realizing that sooner or later the developers to "tighten" its program to change the protocol. For Linux users, then there was the official client in the form of Flash-applications working, however, considerably worse than third-party development. For mobile phones were only unofficial applications.
Members Jabber, where informal customers do notThey never have been banned, but because mobile phones had many such programs could gain access to ICQ via gateways. It - also programs that are running on servers. Like TJAT, they "razgovanivali" to the ICQ server to "understand" his "language", but the interaction with the mobile phone they had to communicate not with a WAP-browser and a Jabber-clients. During the "quiet war" to alternative clients often refused to function, and they are. There have been cases of hacking of gateways, but they were rare.
The situation has changed for the better after the ICQIt was bought from the AOL group Mail.Ru. The new owner has allowed the creation of alternative clients and made it possible for programmers to access the description of the protocol. But on the other hand, the need for informal applications almost disappeared. Initially made in support of ICQ Mail.Ru Agent, to which the official client then already was. Then we released the official ICQ Mobile client with support also Mail.Ru Agent. In fact it had two almost identical programs, which differ mainly in design. Both they interact directly with the server, and soon entered in both programs support Jabber. Turned multi-client, a little different from the third-party development.
Today, the official client ICQ,interact directly with the server, there is for the most common mobile platforms. There is also the official client for desktop computers with Linux, as well as the official web-client running on the same principle as the TJAT. It does not require Flash, and we can use it through a standard browser from a computer or mobile phone.