Mr. Parker rejected the idea that Airtime was struggling. He said there was a dedicated core of people who used it regularly, and he pointed out that the company was still getting its bearings.

“This is a ridiculously early stage for a company,” Mr. Parker said in an interview on Monday at his town house in New York. “It takes six to 12 months to get things up and running.”

Mr. Parker said the company was moving most of its operations from San Francisco to New York, which would help the business by taking advantage of engineers and designers on the East Coast. The company is also working on a mobile version of the service, as well as features that will let people chat with multiple friends simultaneously, rather than just one.

Some of the criticism lobbed at the company came in response to its over-the-top introduction — a star-studded event at a studio in Manhattan, complete with fancy hors d’oeuvres. Mr. Parker said he wanted to grab the attention of those who were not avid technology users and reel in a big group of the curious on the first day. The lingering scrutiny of the company was an “unintended consequence,” he said.

Airtime declined to give specifics about its user numbers other than to say that early traffic was “very compelling.” AppData, a service that collects data about sites and services that connect with Facebook, indicated that Airtime had just 400 users a day and 10,000 over the course of a month, but Mr. Parker and other executives at the company suggested those figures were off. Nielsen and comScore, two independent analytics firms, both said that traffic to Airtime was so small that it did not yet register on their charts.

Mr. Parker said Airtime was monitoring how people were using the service and was adding new features, like the ability to leave recorded video responses. He said it was similar to his early days at other companies, including Spotify, the business networking service Plaxo and even Facebook.