I have an old IAD2421-8FXS and I believe that the DSP module is going bad because calls to and from the FXS ports are coming back with broken voice and low volume. Does anyone know where I may find a replacement DSP card.
The IAD-2421 is End Of Life/End Of Support as of July 2009:
The DSP's aren't FRU parts anyways, IAD is a modular unit and the DSP's aren't an orderable part...even if it still had HW support.
For testing, the syntax for removing a suspect DSP from service is:
router# test dsp device 0 remove
This places the DSP in a "bad" state, then save, reset the IAD.
In this case you'd most likely want to take DSP 1 out of service, since you only have 8 FXS ports.