Dear Nikh,
I have seen the 3 projects and in detail.
MAX 232
tx Micro Controller to t1in of max232 pin11
rx MICRO Controller r1out of max232 pin 12
rx modem t1out of max232 pin 14
tx modem r1in of max232 pin13
Now max 233
Micro controller tx to T1in max233 = pin 2
Micro controller rx to R1out max233 = pin 3
Rx of modem to T1out max 233 = pin5
Tx of modem to R1in max 233 = pin 4
I used a slightly different ttl logic regulator.
This is the only thing, i can think of, that is different from the 3 projects.
Can you be alittle clearer if you know where is the problem ?
Much thanks