gprs gsm modem communication with arduino via rs232 to ttl converter

Hi i am woeking on a arduino project for tracking cars via gps module and gsm network. I have the MTCBA-G-F4 modem from Multi-Tech. i have it connected to the arduino with a rs232 to ttl converter module, so far i have not been able to communicate with the modem. I've built a null modem with handshaking(briged dtr->cd+dsr and rts->cts) Ive also tried various combinations of rx and tx on both sides of the converter module. One thing about the module is that is has 8 pins total (vcc, rx, tx, gnd) and (t2o, t1i, r2o, r21). I am working with arduino pro mini and have the converter module powered by the pin Labled (V, and G) which i asume is short for Vcc and Gnd( maybe not, dont know) i am fairly confident that the issue is either the converter or the modem com through just rx and tx. I have tested the modem on my PC, and have been able to send commands, text, and other basic AT+ commands. I have also done a loop back test on the converter with the same serial port on pc by connecting the tx and rx pins(successful echo). Irunning out of things to try here. Here is the link to the actual project im working on, published on instructables.