interfacing the SIM300 with arduino UNO R3

hi friends....! i bought an GSM SIM300 and arduino UNO R3 ..... i cannot use the gsm sim300 (rx,tx) port directly to the arduino (tx,rx) port.....

whether i have to use separate Serial/TTL converter for my project??????????????

please reply as soon as possible

Please supply a link to the SIM300 as soon as possible.