stop deactivate

That's really mysterious!

And yes, you're definitely not the only one experiencing this, as confirmed by:
a. Terraminds Search - http://dwarfurl.com/3379a
b. Google Custom Search - http://tinyurl.com/23jf6c

The only explanation I can think of is that someone out there is systematically spoofing phone numbers to see if they're on Twitter.

There are sites that allow you to 'fake' an sms message or a call so that it looks like it came from another phone number.

You can prevent someone from spoofing your phone number by adding a PIN to your phone settings in Twitter. To do this:

a. Log into Twitter
b. Go to http://twitter.com/devices
c. Add a PIN to your phone settings in the place provided
d. Click the [Save] button

Please note that if you add a PIN to your phone settings, all your future SMS messages to Twitter must start with that PIN.

For example, if you had entered the word 'secure' as your PIN, then all your future sms messages should look like: "secure Here's the rest of the sms message" (no quotes)

Messages that are sent from your phone number (spoofed or otherwise) without a valid PIN are ignored by Twitter.