NEW YORK -- Owners of Sidekick phones may have lost all the personal information they put on the device, including contact numbers, because of a failure of servers that remotely stored the data.
The incident is a blow to the reputation of the Sidekick and is a reminder of the dangers of trusting a single provider to safeguard information.
The phones are made by a Microsoft Corp. subsidiary and sold by T-Mobile USA, which says many Sidekick owners' information is "almost certainly" gone. T-Mobile is offering customers $20 to refund the cost of one month of data usage on the phone.
Microsoft spokeswoman Debbie Anderson said Monday that there was a still a chance some of the lost user data could be restored from a backup system. Engineers were working at it in the Microsoft data center where the failure occurred, she said.
The phones were troubled by a data outage a week ago. Service was intermittent last week, and then users started reporting that their Sidekicks were wiped of all personal information.
"This has been a terrible experience," said Mary Boyle, of Silver Spring, Md. She lost more than 500 contacts, 100 pictures, a to-do list and dozens of website passwords.
On Saturday, T-Mobile and Microsoft warned customers not to restart their phones, remove the batteries or let the phones run down their batteries. Boyle said she did none of those things, yet her data disappeared anyway.
She switched to a BlackBerry from Verizon Wireless on Monday, and said she had no intention of paying T-Mobile for quitting her contract early.
"As far as I'm concerned, they very much broke their contract with me before I broke theirs," she said.
Although the underlying data services were working again Monday, T-Mobile was still advising customers not to reset their phones. T-Mobile also was listing all Sidekicks as "out of stock" on its website Monday.
It's not clear how many customers have been affected, or how many Sidekicks are in operation, though the figure could approach 1 million, judging by T-Mobile's financial statements. The phone, which exists in several versions, has never been a huge seller since it launched in 2002, but it's very popular among young, urban customers, and it has had a certain cachet as a celebrity phone. Most famously, Paris Hilton used a Sidekick. Users have appreciated its large QWERTY keyboard for text messaging, a feature now copied by mainstream phones.
Microsoft bought Danger Inc., the maker of the Sidekick, last year in an attempt to revitalize its "smart" phone software portfolio. T-Mobile is part of Deutsche Telekom AG.
The Sidekick's remote data storage feature was ahead of its time and served as a selling point for the device. It meant that if someone lost a phone, the contents could easily be downloaded to a new one. But the Sidekick didn't complement the remote storage with a convenient way to save all data locally. Most newer phones, such as Apple Inc.'s iPhone, are designed to back up a user's data when the device is connected to a PC.
Increasingly, consumers and businesses are relying on "cloud" services -- in which e-mail, word processing and other applications store their data in remote server farms rather than on the machines where the work is performed. Providers such as Google Inc. back up the data, but as the Sidekick incident demonstrates, having a local backup can be essential.