I would welcome some input on a client we currently service. Currently they have 40 sites using ESI CS-50 systems with 6 to 8 phones. This will be doubling to about 80 sites in the next two years. Their corporate offices is using ESI's Hosted PBX product. The question that was posed to us was "why shouldn't I pull out the ESI and install a Shoretel or Cisco UC?" They have already invested in the ESI products and could possibly use ESI Link to give them a unified look. We could drop in an IP900 or CS-1000 at the corporate office and link up to 99 sites. Is this what some of you would recommend or would you not even consider going this route? Your feedback is appreciated.