My son just started to receive text messages from:

nobody@server89alphagr.com

The message is a series of numbers, such as:

(3473.3932..9356.2262)
1902.1429.3150.1681.
6307.8548.1004.2895.
8700.8759

And they are coming a couple every minute.  Tried responding with
messages of "stop", "cancel" and "unsubscribe" but they keep coming.
Called verizon customer support and they cannot help (they suggested the
three replies).

Any thoughts?  My son insists that he hasn't signed up for any kind of
"joke of the day" or anything at all using his cell number.

Desperate for ideas!

Dave