Siemens Enterprise OpenStage 40 SIP IP-phone is a great solution for people working in the permanent place. This model features a large display and easy setup of various protocols such as TDM, HFA and SIP.
Lingo is one of the most affordable U.S. Internet phone services. Lingo offers unlimited local and long distance calls anywhere in the U.S., to Canada, and to Western Europe, plus over 25 calling features