Fastrack's response to AT commands from microcontrolle issue

I am trying to make a Wavecom Fastrack Supreme 10 being able to receive AT commands sent by a microcontroller (Microchip PIC16F688).

I have first tried to send the AT+CPIN=xxxx command to register the modem to the network. What I did was sending the characters one-by-one through its UART (in ASCII), ending by sending the CR character.
I have tested the uC by sending the characters to the PC and all of them are received fine.
When I connect the uC to the Fastrack directly nothing happens. I am actually paying attention to the modem’s LED and see if it starts blinking the same way I am sending this AT command from Hyperterminal, to indicate that it’s registered to the network.

Note those settings:
1)On the serial connector on the PCB I have used only the Tx and Rx pins. Both of them are bridged to the uC through a signal translator TTL-to-RS232 and vice-versa.
2)The baud rate of the uC is set at 115200 bps.
3)I have disabled the echo function of the modem by sending ATE0 from Hyperterminal.

Has anyone managed to do something similar succesfully?

And what does the Fastrack User Manual tell you about the signals that it requires…?

Putting “PIC” into the ‘Search’ box would answer that…

Silly question, if the modem needs the CTS/RTS pins (hardware flow control) to communicate with the DTE, how come when I user Hyperterminal with Software Flow control (Xon/Xoff) or none, I can still send AT commands to it?

Probably, the PC’s COM port puts those lines into a “nominal” state? … ck+rts+cts