Two of the big questions surrounding the disappointing Vonage IPO, other than why its keeps going lower, is just how many of the company's own customers bought the stock at the hefty IPO price of $17 a share, and have actually paid full cost for the shares.

Ever since its May 24 IPO,  Vonage has been keeping mum about its direct to share program, which gave its customers - people who purchase the Vonage internet phone service- access to its IPO. Vonage thought it was doing its customers a huge favor and generating some good publicity. It wasn't so long ago that giving small investors access to an IPO was like giving away free money; shares usually spiked as soon as they were open for trading, and investors made a bundle.

The problem for Vonage and its customers was that just the opposite happened; the stock has been in free-fall since the offering, losing 13% on its initial trading day. It is currently trading under $7 a share, and many customers have balked at paying $17 for a stock that is now worth less than half that amount a mere 6 weeks later.

Publicly, Vonage has been tight lipped about how many people are refusing to pay up. But that may be changing; one person close to Vonage told CNBC that the refusals haven't been  as drastic as first thought. This person says that between 60% and 70% of the DSP customers have paid their full amount. The person also says that the exact number will be released in the coming weeks when Vonage announces second-quarter earnings.

Most analysts, however, are unimpressed. What is unclear is exactly how much money these customers have actually paid. Remember, the company set aside 13.5% of its IPO for its own customers. It's unclear if the 60% to 70% represents all the customers who bought the shares -around 10,000-or the total amount of stock set aside in the DSP program. A company spokeswoman declined to provide more details until the release of second-quarter earnings, but its conceivable that most of the DSP remains uncollected even if most of the 10,000 participants paid up.