Students at Boston Arts Academy in Boston use their T-Mobile Sidekicks in February. On Monday, T-Mobile said owners of Sidekick phones may have lost all the personal data they stored on the phone, including contact numbers, because of a failure of servers operated by Microsoft. Credit: Charles Krupa / Associated Press.

T-Mobile said today that Sidekick cellphone owners who experienced a significant and permanent loss of personal content will receive a $100 customer appreciation card. The card can be used toward T-Mobile products and services, or a customer’s T-Mobile bill. This will be in addition to the $50 credit that’s been given to all Sidekick data customers, the company said.

A server failure last week resulted in a loss of contact numbers, calender entries, to-do lists and photos for some Sidekick users. The outage affected customers who were enrolled in the Sidekick's data service provided by Danger, a subsidiary of Microsoft Corp.



“A subset of Sidekick customers appear to have lost data,” the company said in a statement. “We do not have an exact number, but we believe it is a minority of customers.”

T-Mobile voice and text services were not affected during the Oct. 2 outage.

Krista Berlincourt, a T-Mobile spokeswoman, said the company told customers last week that there was a temporary data outage and advised them not to reset their phones, remove their battery or let their battery drain completely. If they did, they were at risk of losing their data, she said.

Sales of Sidekicks were temporarily put on hold, Berlincourt said, even though “virtually all data services are operational,” the company said.

“We have made significant progress this past weekend, restoring services to virtually every customer,” T-Mobile said in today’s statement. “Microsoft/Danger has teams of experts in place who are working around-the-clock to ensure this stability is maintained.”

Customers who are looking for updates and more information on the outage are encouraged by T-Mobile to visit the Sidekick Forums online.

-- W.J. Hennigan