Shares of Blackberry seesawed Friday amid the much-delayed U.S. debut of its new Z10 touchscreen device.

Up to as much as $17.22 in the morning, its stock closed down $1.33, or eight per cent, at $15.19, on twice their usual volume on the Toronto Stock Exchange.

Still, the shares have gained more than 30 per cent since the beginning of the year.

AT&T begins selling the Z10 today, more than six weeks after RIM launched the devices in Canada, the U.K. and elsewhere, for $199.99 US on a two-year contract, the same price as the current version of the iPhone.

Verizon Wireless will begin offering it on Thursday, the same day as BlackBerry comes out with its next earnings report. Sprint Nextel won’t be offering the Z10, but will carry the Q10, BlackBerry’s new keyboard version.

The launch is a major test of the Waterloo, Ont.-based company’s bid to turn itself around and regain market share lost to Samsung, Apple Inc. and devices using Google’s Android operating system.

U.S. sales account for about a fifth of its revenue, but fell by almost half to $520 million US in the third quarter, compared with the same period in 2011.

CEO Thorsten Heins said the company has to regain market share in the U.S. for BlackBerry to be successful. "You got to win here to win everywhere else," he said.

"That's just the way it is. We've lost market share quite a bit, to put it mildly, and we absolutely need BlackBerry 10 to turn us around."

The company received welcome news recently when a corporate client committed to buying one million devices.

Heins said the Q10 won't be released in the U.S. until two or three months from now. He previously said it would be eight to 10 weeks, but now he's saying it could be delayed an additional two weeks.

Heins calls iPhone outdated

At a pre-launch event last night at a theater in Times Square, Heins called Apple's iPhone outdated, criticizing its user interface.

He noted iPhone users have to go in and out of applications and the device doesn't allow for multitasking like the new BlackBerry Z10 does.

"It's still the same," Heins said of the iPhone. "It is a sequential way to work and that's not what people want today anymore. They want multitasking."

BlackBerry's new software allows users to have multiple applications open like on a desktop, he said, noting that with BlackBerry you don't have to close an application to check an email.

"We're changing it for the better because we're allowing people to peak in the hub," Heins said.

Heins said the iPhone was revolutionary five years ago, but he said it's now "just kind of sitting there."

Apple spokeswoman Natalie Kerris declined comment.

But the delay in selling the Q10 complicates RIM's efforts to hang on to customers tempted by the iPhone and a range of devices running Android.

Even as the BlackBerry has fallen behind rivals in recent years, many BlackBerry users have stayed loyal because they prefer a physical keyboard over the touch screen found on the iPhone and most Android devices.

But the temptations to switch grow with each additional delay, despite favorable reviews for new system.

Heins said the Q10 keyboard version BlackBerry is just not ready yet and said part of the reason is out of his control.

"It's our job to deliver the right software package and the right software quality to the carriers," he said.

"Then it is on the carriers to decide how intense they want their testing cycle to be and that really can range from a few weeks to three months."

With files from The Associated Press