I keep getting this text message - why?

[SurreyGuy]

I have received the following text message at least once a day for the past week. Does anyone know what it is about?

T.I.A.

The message reads.......................... [phone] **ALERT** Your prodigy device having Serial ID ******************* is un-reachable. Please check your setup. Prodigy Alert Service.

[koster]

Is [phone] your mobile phone number or someone else's?

Is there a number for the sender?

[SurreyGuy]

[phone] is the sender's number.

It is not the number of anybody I know.