The ICQ system was originally created for communication with the help of personal computers.
But as the availability of mobile phones with access to the Internet increased, programmers began to come up with ways to use this system from them.
Initially, all the applications for this purpose were unofficial, but then official ones also appeared.
In the period when ICQ belonged to AOL, the contractBetween the company and the user it was forbidden to use alternative clients, and the official ones were only for computers running Mac OS and Windows. But in practice for the use of alternative programs, no one was punished. These were created both for Mac OS and Windows, and for OS, where there were no official clients, for example, Linux. A software solution for mobile phones has not yet been. WAP-browsers already built in many of them, but the possibility of launching Java-applications was not all. Therefore, a site called TJAT was created. He worked as follows: an alternative client was run on the server, and a user from a phone with a WAP browser accessed the web interface, entered a number and password, and then got the opportunity to send and receive messages. The server acted as a kind of bridge, interacting with the ICQ server in a "clear" language, and with a WAP browser - on "understandable" to him. Once this server was hacked, and attackers got access to a certain number of passwords. But by that time it was already irrelevant for most users.
This was due to the fact that soon receivedDistribution of phones with the ability to run Java applications. This allowed to create ICQ-clients directly on mobile phones, without requiring an "interpreter" server. Programmers created several alternative clients, the most famous of which was JIMM. From the point of view of the protocol of interaction, it imitated the official client, so the ICQ server willingly interacted with it. Then AOL announced to unofficial clients, including JIMM, a quiet war. The protocol was amended, which reflected in the official client, but the authors of the informal did not immediately have time to decode these changes and reflect in their developments. After several such attempts, AOL surrendered, realizing that sooner or later developers will "pull up" their programs to protocol changes. For Linux users, then there was already an official client in the form of a Flash application, working, however, much worse than third-party development. For mobile phones, there were only unofficial applications.
Jabber users, where unofficial clients do notWere never banned, and therefore there were many such programs for mobile phones, they could access ICQ through gateways. These are also programs running on servers. Like TJAT, they "broke up" with the ICQ server in "understandable" to him "language", but when interacting with a mobile phone they had to exchange information not with a WAP browser, but with a Jabber client. In the period of "silent war" with alternative clients, they often refused to function. There have also been cases of hacking such locks, but they were rare.
The situation changed for the better after ICQWas redeemed from AOL by Mail.Ru. The new owner allowed the creation of alternative clients and enabled programmers to access the description of the protocol. But on the other hand, the need for informal applications has almost disappeared. Initially, ICQ support was introduced in Mail.Ru Agent, for which the official client was already there. Then released the official mobile ICQ client with support also Mail.Ru Agent. In fact, they were two almost identical programs, differing mainly in design. Both of them interacted with the server directly, and soon both programs introduced Jabber support. Multi-protocol clients were obtained, which differ little from third-party developments.
Today, official ICQ clients,Interacting with the server directly, there is for most common mobile platforms. There is also an official client for Linux desktops, as well as an official web client, working on the same principle as TJAT. It does not require Flash, and you can use it through a regular browser both from your computer and from your mobile phone.