Have you tried this code with the PIC connected to your PC running Hyperterm at 9600 Baud?

You should see: atd 453
in the terminal window when you start the PIC.

Once you have got this working you can be sure your Hardware is ok.

You are saying you have already tested the phone and datacable with Hyperterm and it's working.

Are you sure you are connecting
for PIC to PC:
TX from the MAX232 to RX on the PC
RX from the MAX232 to TX on the PC

for PIC to Phone:
TX from the MAX232 to RX on the DataCable
RX from the MAX232 to TX on the DataCable


Before trying to communicate with the phone try to establish a bidirectional communication between PIC and PC.
as long as you haven't got this working there is something wrong in general,
and it doesen't make much sense to connect the PIC to the phone.


regards

Ralph