Call handphone using Microcontroller

Hi,

i am having a big problem which need to be solved within a week.
First, i am doing a simple alarm system. When the sensor detects break in, the speaker will sounds and at the same time, the handphone that is connected to the PIC will call 999 or pre-determined number.

I am done with the Sensor- PIC- Alarm(Buzzer).

Now, i dont know how to do the programming for PIC-Handphone.
I plan to use R2R to generate DTMF tones like below:


I am not sure of the circuit for PIC and R2R. Now, i am just connecting R2R input D0-D7 into my PIC Port D. Is this correct? Then the Output pin and GND pin of the R2R circuit will connect to my Handphone.


P/S: I am using PIC16F877A and i planned to use NOKIA 3310 as the handphone(recycle the phone).

I research online for some time and i am blur now. I saw examples using RS323, MAX ic, Tone generator, Amplifier, GSM modem, SMS, AT command, Hyperterminal. All this making me becoming more and more confused.

Please advice me on how to do the circuit connection from PIC to R2R and Handphone AND also please teach me how to write programming for the DTMF tones in order for my handphone to auto-dial a number while break in happens?


Thanks.
From,
Alice

F-Bus Protocol for Nokia phones
gnokii.org - Documentation