When we began our VoIP pilot two years ago the technology was being hyped, with Alcatel, Cisco and other big-name vendors selling enterprise-size gear and visions of converged voice and data network nirvana. We ran the pilot to determine whether we should replace Syracuse's campus Centrex service with VoIP and what it would take.
Here's advice we wish we'd had up front: Study your voice and data network infrastructure before you start talking to VoIP vendors. We learned the hard way--but luckily early in the pilot--that our Syracuse network needed some key upgrades to support VoIP traffic.
Things started to get complicated when we moved pilot users from the TDM system to the IP network. Because voice can't tolerate normal traffic delays, we had to configure our switches and routers to handle the more sensitive IP voice. We also had to upgrade our LAN from half-duplex 10-Mbps Ethernet to full-duplex 100-Mbps with QoS (Quality of Service) on new Category 5E wiring. The old circuits were prone to voice no-no's--echos, dropped calls and other performance inconsistencies. The VoIP traffic needed new business rules, too, so we created rules that did tasks such as funneling IP phone problems in the pilot area to our own network engineers instead of to Verizon, our Centrex local telco.
We selected Cisco's AVVID VoIP architecture for the pilot mainly because Cisco had the most mature VoIP products and support at the time, and because Syracuse's backbone is built on Cisco switches and routers. It took us one year to build an IP voice design for our test (see Step by Step), with occasional help from Cisco.