Sales of the new BlackBerry in the UK have been better than expected, the chief executive of Canadian maker Research In Motion has said.
But Thorsten Heins added that he is disappointed it will not be released in the United States until mid-March.
In an interview with The Associated Press, he said the US and its phone carriers have a rigid testing system.
"We need to respect that. Am I a bit disappointed? Yeah, I would be lying saying no. But it is what it is and we're working with all our carrier partners to speed it up as much as we can," he said in the interview at the Ritz Carlton in Toronto.
RIM unveiled new BlackBerrys last week after excruciating delays allowed Apple, Samsung and others to build commanding leads in the industry. Its shares fell 12% after Wednesday's launch, despite positive reviews about the new BlackBerry 10 operating system.
The first device in the new crop of the much-delayed revamped BlackBerrys on the US market will be the touchscreen Z10. Black and white versions were released in the UK last Thursday and will be launched in Canada on Tuesday.
Mr Heins said a substantial number of UK users are moving from other platforms to BlackBerry and said that is an encouraging sign because they first targeted long-time BlackBerry users.
"It's beyond expectations," he said. "White is sold out already. The black is hard to stock up again. It's very encouraging. I won't share the number because I need to verify it, but we are getting a substantial number of users moving from other platforms to BlackBerry. That is an interesting data point."
Mr Heins said they have to retake market share in the US for BlackBerry to be successful. The US has been one market in which RIM has been struggling, even as the company is doing well in many places overseas. According to research firm IDC, shipments of BlackBerry phones plummeted from 46% of the US market in 2008 to 2% in 2012. The iPhone and Android now dominate.
Mr Heins, who a year ago replaced long-time executives who had presided over BlackBerry's fall, said he is confident that BlackBerry can become the third ecosystem behind Apple and phones running Google's Android operating system.