Provided by Advanced IP Pipeline

So which service provider is the guilty party trying to block Voice over IP servicesfrom Vonage Holdings? Not us, said two of the nation's largest telecom service providers, SBC Communications and Verizon Communications.

In email messages this week, spokespersons for both SBC and Verizon said their companies aren't the ones responsible for attempts to block Vonage's VoIP service. However, only Verizon responded to an additional question about whether or not the company could or would employ such blocking tactics in the future.

In an email reply, a Verizon spokesperson said: "We are on the record in a letter to the FCC stating that we would not deliberately block or impair Vonage's or any other non-affiliated VoIP provider's services over our customer's broadband connections."

SBC's reply was: "In response to your question [about the Vonage incident], we can say it is not us." The SBC message added: "we don't have someone able to comment [on the second question] at this time."

At the Silicon Flatirons conference earlier this week, Qwest CEO Richard Notebaert was asked a similar question about whether his company blocked Vonage, but did not answer fully, only to state that "we [Qwest] have a commercial contract with Vonage."

Brooke Schulz, Vonage's vice president for corporate communications, said this week that Vonage used to have a contract with Qwest for wholesale bandwidth, but no longer does.