As of Sunday, all models of the Sidekick were listed as "temporarily out of stock" on T-Mobile's Web site.
T-Mobile retail store workers also said on Monday that they have been instructed to halt new sales of the device as the company continues to investigate the recent problems that have plagued the handheld.
To recap, Sidekick customers started experiencing problems connecting to the data network more than a week ago. Microsoft, whose Danger subsidiary powers the Sidekick service, said it was investigating the problems.
On Saturday, Microsoft and T-Mobile posted an updated notice saying all data that was not currently on customers devices was likely lost permanently.
["Sidekick customers, during this service disruption, please DO NOT remove your battery, reset your Sidekick, or allow it to lose power."]
Microsoft and T-Mobile have not said how many of the roughly 800,000 Sidekick customers have lost data. Microsoft said a server failure impacted the main and back-up databases. One theory is that the problems cropped up as Hitachi was doing work on the storage network that manages the Sidekick data.
T-Mobile has promised an update for customers sometime Monday. For now, the carrier has advised customers not to reset their devices, remove the battery, or let them run out of power, as doing so could result in losing whatever data they do have.
Microsoft acquired Danger last year, saying it hoped to use its service architecture more broadly in its mobile strategy. The software maker has been working on a project code-named Pink that was to be essentially the future of the Sidekick. The company had not planned for any more versions of the current Java OS-based Sidekick.
By CNET's Ina Fried