Asterisk Hardware
Asterisk May Not Work Well With Any Hardware and Software
The misconception is that Asterisk can run on any old PC. While that is true, to get truly great performance from Asterisk you must have the appropriate hardware. Investing in hardware without knowing what you difficulties/problems might be up for is 
disastrous.
We have spent 100s of hours in testing varieties of servers, appliances, Analogue terminal adaptors (ATA), modem cards and handsets that are suitable for Asterisk.
Sometimes your Asterisk may require extra Codec (software).
It may not be appropriate to list all the hardware we tested and found to be compatible or incompatible but you can give us a call and ask for advice on.