information about hardware:

  information about hardware: what are the ways that can we connect phones with arduino and DTMF? and what are the ways that can we connect phones with raspberry and DTMF? what is the best, using serial communication or parallel communication? the second part: why we use keypad phones(old phones) in connecting phones with DTMF. and why we use new phones(smart phones) in connecting phones with DTMF. what are the advantages and disadvantages of both old and new phones and which one is better to use in connecting phones with DTMF.