Hi,
If you would like to get to know about audio compression
and you want to do it with pic, try microchip appnote: an643.
(You can download it from microchip web site).
It describes the adpcm method, and it gives examples and
advices for adpcm usage on various pics.
On the other hand, I think you don't need to worry about
audio compression in this case, you can use the isd devices.
The isd is an analog storage eeprom.
For example the isd2560 can store 60 seconds,
it has 3.4 khz bandwidth, (so it is ideal for phone applications),
it is capable to handle multiple messages,
and very easy to interface with pic (and other mcu).
You can find more info on the web site: http://www.isd.com.

bye
csaba

>Hi all,
>
>I'm thinking of building a digital telephone answering system. What I
>really want to know is if there are any good audio compression
>algorithms that I can use.
>
>I'll be using a PIC processor preferably with a multiplication
>instruction. The algorithm can't be too complex because you need to
>compress the data in real time (8 bits, say 10kHz).
>
>Is this possible or are you better off just storing the audio data
>uncompressed? What do you think?
>
>Regards, Danjel McGougan.
>
>