Business phone system recommendation

We are a small 3 person corporation with very modest phone needs but it is apparent our system needs upgrading.

If anyone could recommend a phone system that would be suited to our needs I would greatly appreciate it.

We are on Vonage.

We need a basic waiting system for customers that call while all attendants are busy.

We need to be able to enter an intro message for calls waiting to be answered instead of the phone just ringing non-stop.

We need to be able to change the message and immediately direct them to leave a voice mail during after hours and non-business days.

Any suggestions? Currently we are using multiple 5.8 Ghz Panasonic phones, but that is just not working.

Get the Asterisk open source phone server. A bit of a pain to setup, but the control of running your own PBX is great!
You'll need a server with a line card and a PRI from a VoiP provider, and maybe a few hours setup time. Well worth it.

You can also try HostedPBX.com or a site like that.

Can 3 people actually make up a 3 corporation? I thought that would be a partnership of sorts? Anyway, I would say any mobile device like a Blackberry or iPhone. Personally, I like the iPhone but a bit expensive for many.

Technically it only takes one person to make up a corporation, which would be called a "close" or "closely held" corporation. A corporation is a legal designation, not a head count.