WO 01/26245 PCT/KR00/00057 DATA TRANSMISSION SYSTEM USING RADIO TRANSCEIVERS TECHNICAL FIELD The present invention relates to a data transmission system using radio transceivers and, more particularly, to a innovative data transmission system without dedicated communication lines using radio transceivers so that the cost of operation and maintenance of the system can be reduced and the security of transmitted informations can be guaranteed. BACKGROUND OF THE INVENTION Recently, with the spread of cellular phones, character transmission services that enable character data to be transmitted between cellular phones have been available. In the character transmission services, characters input to a cellular phone by a user are encoded into character data in the processor of the cellular phone and then transmitted to another user's cellular phone through a relay center of a cellular phone company. In another user's cellular phone, the received character data are decoded into characters in the processor of another user's cellular phone and the characters are displayed on a display portion of the cellular phone. And also, recently, on account of the functions of individual radio transceivers such as cellular phones that are available to character transmission services, a number of character transmission services which transmits short texts such as internet e-mail, stock information, and weather forecasts have been developed and provided. 1 WO 01/26245 PCT/KR00/00057 Fig. 1. represents a block diagram of a conventional data transmission system for the character services, and is illustrative of an example of a data transmission system transmitting internet e-mail to a user's cellular phone. The data transmission system consists of carrier 2 such as cellular phone company, relay company 4 connected to carrier 2, and server 6 operated by information provider (IP) 8. The server 6 serves as a E-mail server when users or client transmit e-mail through internet. The relay company 4 is connected to respective carrier 2 through dedicated communication line in order to connect each other at any time, and the IP 8 is connected to the relay company 4 through internet. Thus, in case that user connects with internet and send a e-mail through internet to the server 6 with his internet terminal 5, the server 6 transmits the e-mail to relay company 4. And then the relay company classifies the received e-mail transmitted by the server 6 and transmits the e-mail in the form of character data to the corresponding carrier 2. Upon the receipt of the character data, each carrier 2 encodes the received character data and transmits the data to each user's cellular phone 10 through his owned relay center. Finally, the data which are transmitted to user's cellular phone 10 are decoded and displayed in the form of characters. According to the types of IP's 8, the above mentioned data transmission system can be broadly used to applications such as transmissions of bank account details, stock information service of security company, credit transaction details of credit card company, work orders of transportation company as well as e-mail transmission. 2 WO 01/26245 PCT/KR00/00057 But, the above mentioned data transmission system has problems. One of the problems is that the construction of the above mentioned data transmission system is not only complicated and also increases cost for dedicated communication line 11 because the relay company 4 and the carrier 2 are always connected with the dedicated communication line 11. And another problem is security problem, that is, the content of e-mail is exposed to the relay company 4 and the carrier 2 because the e-mail are supplied in the form of characters. Particularly, when the data communication systems are used in banks, stock companies, credit card companies, and transportation companies and so on, the problem about secret preservation between clients and companies is very critical since client's account details, company secret, working status and so on are completely revealed to relay company 4 or carrier 2. Therefore, a new concept of data transmission system is needed to reduce cost as well as to be able to maintain secret. SUMMARY OF THE INVENTION In order to overcome the above-mentioned problems, an object of the present invention is to provide a innovative data transmission system using radio transceivers with which cost can be reduced without any dedicated communication lines and which can maintain secrete for transmitted information. As a aspect of the present invention, in a data transmission system for transmitting a predetermined data being provided by IP 8 to a first 3 WO 01/26245 PCT/KR00/00057 radio transceiver 10 of a receiving user side, the data transmission system comprising: a server 6 operated by the IP 8; and a second radio transceiver 16 of a sending user side connected to the server 6 , wherein the server 6 being provided with a control program to control the second radio transceiver 16, and data of the server 6 input to the radio transceiver 10 being transmitted to the radio transceiver 16 through a relay center 9 of a carrier. Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a presently preferred embodiment of the present invention, and together with the general description given above and the detailed description of the preferred embodiment given below, serve to explain the principles of the present invention. FIG. 1 is a view illustrating the conventional data transmission system; FIG. 2 is a view illustrating the conventional data transmission system using a radio transceiver according to the embodiment of the 4 WO 01/26245 PCT/KR00/00057 present invention. DETAILED DESCRIPTION OF THE INVENTION There will now be described the preferred embodiments of the present invention with reference to the accompanying drawings. Although the present invention is described though the cellular phone telecommunication system, the present invention is not limited to the cellular phone telecommunication system and further applied to any wireless or radio telecommunication system. The term " radio transceiver" in the specification refers to a wireless or radio telecommunication terminal such as cellular phone, CDMA and TDMA handsets, Iridium handset, pager, international mobile telecommunication 2000(IMT-2000) handset so on. Fig. 2 is a view illustrating the conventional data transmission system using a radio transceiver such as cellular phone according to the embodiment of the present invention. With reference now to Fig 2., the e-mail data transmission system using a radio transceiver 16 for transmitting character data to the receiver through the relay center of carrier includes server 6 operated by IP 8 and a plurality of radio transceivers 16 parallel-connected to serial ports of the server 6. The server 6 which functions as a server of receiving e-mail and then classifying and identifying it, and it is provided with a control software for controlling the radio transceiver 16. The control software functions as inputting whether a e-mail is received, the information of e-mail, for example, the content of e-mail and the number of e-mail or likes, and the receiver's phone number to the radio transceiver 16. 5 WO 01/26245 PCT/KR00/00057 Thus, user transmits the e-mail including the receiver's phone number to the server 6 using his own internet terminal through internet, and then the server 6 receives the e-mail and classifies and identifies it to construct database. And then the server 6 transmits the e-mail information and the phone number written in the database by inputting them to the radio transceiver 16. The e-mail information input to the radio transceiver 16 is encoded and transmitted to the receiver's radio transceiver 10 through the relay center of carrier 2. The e-mail information is received and decoded at the receiver's radio transceiver 10 and then displayed in the form of characters. Alternatively, instead of being parallel-connected serial ports of the server 6, the radio transceivers 16 may be connected to other ports of the server 6, or only one radio transceiver 16 may be connected. According to the data transmission system of the present invention, since the data transmission system can transmit the predetermined information to the receiver with the radio transceivers 16 and 10, any additional dedicated transmission line is not required and so the cost of maintaining the system is reduced. And Also, since the information supplied to the receiver is transmitted after being encoded, apart from the conventional data transmission system in which the data in the form of characters may be revealed by the relay company 4 and/or carrier 2, the data transmission system according to the present invention makes sure of security of the information. Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices shown and 6 WO 01/26245 PCT/KR00/00057 described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 7