Cannot Communicate with Modem: Nokia 7110

[gruveemaan]

Hi,
I am trying to connect my mini877 board and use it to dial out using a phone as a modem (using a DLR-3 cable). I am not seeing anything coming back to the pic board from the modem when I send the "AT\r" to the phone.

I know I am sending the "AT" string OK, because when I connect the pic serial port to the hyperterm, I see "AT" displaye on the hyperterm and when I press a key on the hyperterm, I see the received character on the pic.

If I use the hyperterm and connect it to the phone and send "AT", I get an "OK" back.

Note: I am communicating with the phone ONLY using 2 wires (TX/RX)from the PIC board

Kindly advice.

[Neutone]

Are you saying that you are not using a signal ground? Just 2 wires?

[gruveemaan]

Sorry for the confusion. I am only using TX/RX

[gruveemaan]

Opps! forgot to mention GND. These are the only 3 wires that are available on the CCS 877miniboard.