Is there simple way to find out what Comdial System and voicemail I have? I know that the phones are 8324SJ phones.
Go back to your telephone/computer equipment room and look for some piece of equipment that has "Comdial" on it. I have quite a few of those phones that are supported by Comdial DSU II systems---a grey steel oblong box (cabinet) approximately 2 ft wide by 3.5 ft long and 3 or 4 inches deep--should be hanging on the wall. Google DSU II. These phones are also supported by other Comdial systems, however. Google Comdial FX II.
Ok it appears to be a Comdial FX II system. Thank you for that.
Is there a way to verify the voicemail system?
It's probably a KeyVoice voice mail---but it could be almost anything. Look for a PC-like cabinet. However, as was said---it could be almost anything.