I am looking for a headset that is wireless to use VoIP. I have seen some with USB connections but don't know which one to buy. which one and where to find them.

The only phone I have is connected to the router, but if I plug in another phone into a phone jack on a wall, it doesn't work? Can anyone help?

basically we have 4 phone lines. 1-2 being the main lines. 3 and 4 being the phones that we use through the internet. However when I am on the phone talking to someone, and another person in the office sends an email, it cuts me off until the email has been sent. Why is this?

I'm trying to determine if a 1 Mbps downstream and 512 kbps upstream is sufficient for a 5 person office. The network needs to be able to handle multiple calls at the same time.