T-Mobile and Microsoft may have had carnal relations with the proverbial canine, thanks to a massive failure followed by apparent permanent loss of personal contact, calendar, and other data with the Sidekick, a phone sold by T-Mobile and powered by Microsoft-acquired Danger. I saw the initial phase of this problem first hand a week ago.

We had just returned home with a high school buddy of my wife's after attending a performance of the touring show of Wicked when her friend tried to check his T-Mobile Sidekick smartphone, on which his business depends. No dice.

We tried charging the phone, restarting it, logging in via the Web - all to no avail. It quickly came out that there was a complete outage of services from Danger, the Microsoft-acquired firm that runs the back-end servers for the Sidekick.

Unlike many smartphones, Danger-based phones store data in a cloud - servers located hither and yon that you don't manage, but are imagined to be universally and continuously accessible. These phones retrieve information as necessary and cache a temporary copy on the phone, a copy that's not intended to be a permanent set of stored records. The data also isn't intended to be synced to a computer as with a BlackBerry, iPhone, Android, or other smartphone, but accessed via a Web site or a phone.

It sounds more like the Sidekick data lives on something akin to an IMAP server: you can have some local copies, but the server is master. With IMAP, the copies persist even after a computer or phone restarts, of course, just as you might expect. But in the Danger approach, locally cached data is erased on restart or if the battery runs out of power.

Our friend had his service restored the next day, although some Sidekick users were out of luck for days, or apparently suffered a separate outage. (The reports talk about an outage on 06-Oct-09, while our friend's was down on 03-Oct-09.)

Now the kicker - or the sidekicker: any personal data that's not still on your Sidekick is likely gone forever due to server problems, T-Mobile said in a statement on 10-Oct-09.

It is frankly breathtaking that there's any conceivable way in which one could run a service in 2009 - or 1999 for that matter - where some form of server problem would take down not just live data for customers, but - as far as T-Mobile has said - any previous copies as well.

T-Mobile advises customers who have cached data still in their Sidekicks to avoid running out of power, restarting, or shutting down their Sidekicks, lest the last chance of recovery be lost.

I can't imagine the aftermath of this event. T-Mobile is already the distant fourth cellular carrier by subscriber numbers in the United States, and, like Sprint Nextel, has no landline phone or broadband business with which to pair its offerings.

Having a massive, unprecedented data loss - even if this turns out to be entirely Danger's fault - will likely mean an exodus of high-value customers, who will certainly not be obliged to pay - or will sue to not pay - any contract cancellation fees.

Are other smartphone platforms immune? Why, yes, they are, as a general statement. iPhone (and iPod touch) users who sync via MobileMe wind up with their data stored in many places, and only some corrupted sync operations, coupled with the deletion of automatic backups could wipe contacts, calendars, email, and other data. In other words, as far as we know, it's difficult to imagine a situation in which Apple could make an operations-related mistake that would destroy all iPhone data for a significant percentage of users.

Android users synchronize via Google services, and unless an Android user destroyed his or her Google account or manually deleted all contacts, calendar events, and other data, there would still be copies available elsewhere. Since Google services are easily synced to computers, it's likely that copies would be accessible in Address Book and iCal as well (or comparable programs in other operating systems).

BlackBerry users may be at some risk, because Research in Motion (RIM) relies on centralized servers for push email and other features, but RIM doesn't use a cloud to store data for customers, and BlackBerries have locally stored address books, email, and other data. And, again, it's possible to sync BlackBerries with computers, providing yet another copy.

With these three platforms, unless you wiped your data everywhere, or synced after wiping or losing data in such a way that it synced an empty set everywhere (and there was no local hard drive backup, too), you'd still be able to restore everything, or at least nearly everything.

Windows Mobile, the Nokia-backed Symbian platform, and Palm's webOS have no monolithic central storage system, so smartphones based on these three platforms can't suffer from such problems.

Generally speaking, the Sidekick data loss disaster appears as though it's unique to a cloud-oriented mobile service company. And so, the moral of the story is, be wary of services that store essential information in a cloud without options for making local backups, preferably in an automated fashion.