Does anyone know how to read the DTMF signals into a PIC 16F84? And how to connect the output binary lines to the input of the PIC?

Basically I want to be able to connect a phone to a 8870 DTMF decoder and have it so that if I enter a certain code (ex...*123#) on the telephone than the 8870 will decode it, and spit out the binary values to the PIC. Once the PIC receives the values I can have it scan the inputs, if the code is correct (*123#) than I can make the outputs do somehing...

Any assistance or example would be greatly appreciated!