Why is Vonage lying to it's customers?

Vonage is a VOIP phone company that advertises it's service as "it sounds just the same as any other call" and "Your callers will never know that it's any different since it sounds just like a regular phone call." These quotes are takend from this vonage.com page. Their TV ads say similar things.

I've had the service for years, I just don't need a real phone with my cell phone and internet. I can tell you that it's not just like a real phone. The quality is closer to a cellphone call than a real call sometimes.

Now that Vonage is going public, they have detailed some of their problems in thier Prospectus. For example, they detail how their calls are different than a regular call:

Certain aspects of our service are not the same as traditional telephone service. Our continued growth is dependent on the adoption of our services by mainstream customers, so these differences are becoming increasingly important. For example:

Both our new E-911 and emergency calling services are different, in significant respects, from the 911 service associated with traditional wireline and wireless telephone providers and, in certain cases, with other VoIP providers.
• Our customers may experience lower call quality than they are used to from traditional wireline telephone companies, including static, echoes and delays in transmissions.
• Our customers may experience higher dropped-call rates than they are used to from traditional wireline telephone companies.
• Customers who obtain new phone numbers from us do not appear in the phone book and their phone numbers are not available through directory assistance services offered by traditional telephone companies.
• Our customers cannot accept collect calls.
• In the event of a power loss or Internet access interruption experienced by a customer, our service is interrupted. Unlike some of our competitors, we have not installed batteries at customer premises to provide emergency power for our customers' equipment if they lose power, although we do have backup power systems for our network equipment and service platform.

It's just sad that vonage can't admit these faults to new users. I find it funny that they are more honest to the wall street crowd than their main street customers.