Blackberry has launched a distinctive handset featuring a square screen and a keyboard that offers both physical keys and touch-enabled gesture controls.
It said work-focused users in particular should benefit from the Blackberry Passport?s innovations.
Sales of the company?s handsets ? which are powered by its own operating system ? have been in decline.
Analysts said the new device should appeal to existing Blackberry owners but might struggle to win over others.
The Canadian company?s chief operating officer said the handset?s release was part of a broader turnaround strategy led by John Chen, who became chief executive in November.
?You?re going to see us be very focused,? Marty Beard told the BBC.
?Potentially, in the past we got a little too broad a little too aggressively.
?Our target segment is more enterprise-focused. It?s the power professional. It?s someone who wants to be productive.
?Those users tend to be in regulated industries like banking or healthcare or government. We know those segments really well ? in a way it?s getting back to the Blackberry roots.?
The Passport got its name because its dimensions resemble a thick version of the travel document.
It has a 4.5in (11.4cm) touchscreen with a resolution of 453 pixels per inch ? higher than Apple?s iPhone 6 Plus, but lower than Samsung?s Galaxy Note 4.
Blackberry suggests documents are easier to edit because of the extra width provided by having a square screen, even if it is less suited for watching video.
The keyboard buttons are also touch-sensitive. This allows gesture-based shortcuts that were previously restricted to Blackberry?s all-screen devices.
For example, swiping a finger quickly leftwards along the keys deletes the previous word, while sliding a thumb along them more slowly moves the cursor in the same direction.
In addition, users can select from three anticipated words ? shown near the bottom of the screen ? by flicking upwards beneath the desired one. This saves having to type the text in full.
?In some cases it takes a while to learn it, because even if you?re familiar with a Blackberry it?s a little bit different because it?s that combination of physical plus virtual,? acknowledged Mr Beard.
?So there may be that learning curve in the beginning, but it?s well worth it, and once people learn it they are flying.?
One expert who has tested the handset supported the claim.
?It certainly made me respond more eloquently to emails rather than just triaging them with a ?Yes, no, I?ll call you back or see you later?,? said Shaun Collins, founder of the telecoms consultancy CCS Insight.
?However, it?s going to divide opinion ? it gives you the Blackberry experience on steroids. But for a broader audience it will be a curiosity.?
The phone is being sold at an ?introductory rate? of $599/?529/649 euros.