its visible problem i feel in 2 fold ways...
modem gets message when sent from mobile as the max232 rx is working fine on modem and controller side. and cable is correct.
when modem should transmit then, AS modem it is sending so problem happens in the MAX232 of modem or pin 2 of cable on modem side ..
please do the following and let me know....
1. serial cable loop back test.. short tx and rx and typr to see you get same data on terminal, if not the there is some problem in cable.....
2. if works fine then short tx and rx and do the same test in power ON condition.. make sure you dont short it for a longer time....
please reply to me after doing this..