I strangely get mysterious text messages only containing a number. They do not appear in the messages-app - I can only click "OK" then they're gone.
Here is a screen-shot:

The number is different each time. The issue is really annoying since they trigger the standard SMS-notification behavior (including ring-tone and vibration) and I get them every 5 minutes. I've had this problem since I bought the phone in early July, the FroYo Update did not solve it.
Can anyone help? Is it better to contact the provider?
Background-Info:
Android 2.2 with O2-Branding, AMOLED Desire
