Remember those old SUN Microsystems commercials? “This is my dog, network. He can get you anything you need”. Well, regardless of the vendor, if you have a network that can barely keep up with user demand for internet access, you are definitely not going to have a successful VoIP deployment. This is why a network assessment is absolutely essential to the future success of your VoIP deployment. Let’s start at the lowest level of the OSI model and work up; cable or level 1. It is the 21st century but your company still has CAT3 cable in the office? This is not going to fly if you want to run VoIP do the desktop! How about those Ethernet switches you bought off eBay three years ago? Are they able to provide Power over Ethernet (POE)? Can you enable VLAN's? How about interVLAN routing (switch many time, route once)? Ethernet switches and the functionality you need at L2 are mission critical in VoIP deployments. How about L3? If you are using your firewall for a router, you will need to know that "deep packet inspection" necessary to the functionality of a firewall, is a major source of latency in VoIP deployments, so find another default gateway! When you set up a WAN between your far flung, geographically dispersed business locations, will you have access to them? Or will you need to call your carrier every time you want to check your egress queue for QOS? At the end of the day it really will not matter if you went with Mitel, ShoreTel, CISCO, Avaya or Trixbox. If you do not have a properly engineered and managed LAN/WAN in place your VoIP deployment will suck and you will irritate your boss and alienate your users. Get both a network assessment and an ongoing monitoring and network plan in place, including an “acceptable use” policy before you deploy a VoIP solution.