Almost any switch will do just fine if all what you have on it are the A800.
The trouble is if you have the A800 on the same network than computers users, specially if you do not control those P.C.
If you are trying to pass calls and someone is downoloading the lates porno, the voice quality will suffer if you do not have bandwith or the delay goes up.
But if you are not bandwith poor, and the only thing on the network are the a800, any switch will do.
Calculate 15-20 kb per call to have a safety margin. If you multilply the ammount of channels times 20, and still have bandwith, you are very safe with any switch.
As long as you do not have any teenagers daughters downloading music clips on the same network……
O yeah, I read that in a book. My teens will never do that (again).