By Mark Ward
Technology Correspondent, BBC News website
A gadget beloved of tabloid darlings such as Nicole Richie and Paris Hilton, the Sidekick II, has made its way across the pond to the UK.
Some celebrities are keen Sidekick II users
The mobile phone come handheld computer
has become widely known in the US because of its celebrity fans.
This is partly the result of the guerrilla marketing techniques used in its early days when the company behind the device, Danger, made an effort to put the device into the hands of photographers, designers, artists, models and journalists.
Designer versions of the Sidekick II by Juicy Couture and Mr Cartoon have only helped to boost its profile and desirability. Unplanned production shortages have also contributed to its exclusivity.
The irony for Hank Nothhaft, head of Danger, is that the company does not actually make the gadget, but instead is responsible for the software in it.
The Sidekick II that T-Mobile has promoted in the US, Germany and now the UK is made by Japanese electronics giant Sharp. Earlier versions were made by Flextronics.
Even the name is T-Mobile's choice. When Danger's gadget was first released it was called the Hiptop.
For Mr Nothhaft, the handset fulfils the same role as all the free CDs net service firm AOL used to send out to get people to sign up.
"We needed some means to get the client software in the hands of consumers," he said.
Size: 129mm x 66mm x 23mm
Talk time: 4.5 hours
Standby time: 2.5 days
Tri-band GSM and GPRS
Memory: 32 MB ROM and 16MB Flash
Onboard: Web browsing, instant messaging, e-mail, multimedia messaging, address book, to do list
Price: Free or £49.99 (depending on price plan) plus £30 per month data deal
Because of that he said Danger was keen to get other electronics firms interested in making gadgets that can run this software. He expects some of these other incarnations to start turning up soon.
Far more important is the software on the handset and in the network of the operator taking on the device. Dangers makes its money from licence payments for this software, not hardware sales.
Mr Nothhaft said Danger had worked hard to ensure that the Sidekick was easy to use and navigate around even though it is aimed at tech savvy 18-34 year-olds who blog, post pictures online and use instant messaging.
As the Blackberry is for business users, so the Sidekick is for younger, trendier people.
In the handset software Danger has included hooks into popular online e-mail services, instant messaging networks and every owner gets their own webspace in which to post the pictures they take with the device.
Letting people use existing e-mail accounts stands in contrast to many other smartphones and handsets that force people to use the messaging service of their network provider.
It is this flexibility of use, believes Mr Nothhaft, that has driven up the gadget's popularity. According to figures gathered by Danger, 45% of those buying a Sidekick do so on the recommendation of a friend.
Statistics gathered by Danger suggest that Sidekick owners are heavy users of mobile data services. The average user sends up to 1,000 instant messages and 350-400 e-mail messages per month.
The Sidekick II screen flips around to reveal the keyboard
Getting people using mobile data services to use is going to be key for operators in the future, said Mr Nothhaft.
"Its clear that they cannot grow the voice side of the business," he said not least because third-generation mobile technology gives networks so much capacity that the costs of voice calls will drop towards zero.
"There is also a perception by the carriers that they could create their own content and portals," said Mr Nothhaft, "and it was not that important to provide support to the open internet."
Many are also sticking with monthly tariffs for data services rather than a flat rate.
There was little doubt, said Mr Nothhaft, that having a meter ticking way in the background stops people using the net more from their phones.
Flat rate pricing gave a huge boost to home net services and Mr Nothhaft expects the same to happen when mobile operators do the same.