[cisco-voip] Understanding DSP Resources

[Kenny Kant]

I have a basic question on the general purpose of DSP's  and when they
are required.  From reading on this list and NetPro and other books I
understand that DSP (Digital Signal Processors ? ) are hardware chips
that come shippped on SIMM type modules.  Do they ever come built onto
the board on the newer ISR's  ?

The main purpose of these chips are to "encode" calls that come in over
PSTN interfaces into PCM audio that can be then transmitted via voice
call? Correct?  This is why sizing DSP's to match your incoming PSTN
sourced channels is important.  ???

Another function of these things are to transcode streams to and from
higher compression streams such as G729.00  These are done via DSP
farms.  I hear alot about DSP farms used for conferencing ..etc what are
some other purposes here.  In general, if you are not doing advanced
call conferencing and/or transcoding is there a need for DSP's in CME
system for general calls ephone to ephone ?

Last, can a ISR do any type of transcoding in software? or are DSP's
always required?


Thanks for helping out a newbie :)

Kenny