In a message dated 11/19/99 5:16:19 AM Eastern Standard Time, shrish@USA.NET
writes:

> Hi,
>    I am interfacing a DTMF Transceiver Teltone 8888 to PIC16C74A .This
>  chip has a single output pin for transmitting the DTMF signals. Does anyone
>  know how does this interface to the telephonelines. Basically two issues:
>     - which telephone line should I connect it to
>     - can it be connected directly (i.e. are there chances of any damage
>       to the chip because of the high voltage)
>    I could have tested this, but I am a bit reluctant because I don't want
to
>  damage the chip.
>    Any help in this regard is deeply appreciated.
>    Thanks,
>    Shrish
As I recall, the 8888 outputs the audio DTMF signal.  To interface this to
the telephone line, I use a Motorola MC34014 speech circuit.  With a bridge
rectifier for polarity guard and a few resistors and capacitors, it works
great.

Max