Monday afternoon, Comcast CEO Brian Roberts took on his toughest challengers--the Wall Street skeptics.

Armed with facts, figures and aggressive plans for future services, Roberts used his presentation at the 15th Annual Smith Barney Citigroup Entertainment, Media and Telecommunications Conference in Arizona to make the case that Comcast is done spending billions of dollars and poised to start collecting same.

The message is an important one because Wall Street continues to view cable companies skeptically, even as they position themselves to attack the voice services revenues of their archrival telephone companies. Comcast’s stock was up 2% to $33.23 following today’s announcement of its voice over IP plans, but lost almost half of that gain immediately in after-hours trading.

Roberts began his presentation with a forceful defense of Comcast’s future. "We have a sustainable growth model with tremendous financial strengths," he said. Highlights include "a 20% to 30% growth in pre-cash flow" in addition to "a great balance sheet, and lots of monetizable assets" he added. "We can point to innovation, differentiation and leadership with our scale." More importantly, Roberts said, Comcast has completed its $39 billion investment (including money invested by acquisition target AT&T) since the 1996 Telecom Act to upgrade its network.

"While others are promising to invest billions, ours is behind us," he said. "We now have multiple products, multiple revenue streams. We think of ourselves as a new product company. We don’t believe there will be a next upgrade."

Roberts promised that Comcast is creating a seamless national network that will not only delivery high-quality voice, high-speed data and entertainment video with more choices but also integrate the three, in terms of function, control and customer service. "We will integrate the platform, not run with silos," he said.

The VoIP service, informally announced earlier in the day, will be based on a private IP network and come equipped with battery backup and a wide range of features, leading up to videophones at a future date. Roberts was careful to distance Comcast’s VoIP from that of Vonage and other price competitors.

"Long-term, it’s an important distinction," says Michael Paxton, analyst with In-Stat. "They are not going after people who just want a cut-rate value play. They are going after the higher end subscriber households--that’s who Comcast is targeting with their triple play."

Roberts also emphasized his company’s expanding video-on-demand service as a major differentiator. The company now has a library of 3000 programs, including movies, sporting events and TV shows, and will expand that to 6000 shortly, possibly hitting 10,000 programs by year’s end.

"We had 62 million VOD orders in November," he said. "In Philly, [when the service has been available longest] 80% of our customers have accessed the service within the last 60 days, with 23 orders per month per average household," he said. "We are changing television, and it has cost us virtually nothing to do. What you get for the $39 billion investment is that churn is reduced by 20% to 30%."

Churn reduction is the primary benefit of VoD, says analyst Paxton, because Comcast makes very little money on the service itself. "The revenue is not significant," he said. More than half of VoD programming is free.