A good gauge of the growth rate of enterprise VoIP can be summed up with the following excerpt: It took us 4-and-a-half years to sell our first 2 million IP phones and only 14 months to climb from 2 million to 4 million phones sold to customers, said Barry OSullivan, vice president and general manager for Ciscos IP Communications Business Unit. If you break it out, that equates to a rate of 37,000 phones per month for the first 4.5 years while the more recent rate is 143,000 phones per month. Interestingly a similar trend is happening across medium and small enterprises as well. These growth rates are indicative of the entire enterprise market based on my conversations with vendors in the industry.