Strange messages received on BB from JAMSTER

[udontknowjack]

I have a user at my company getting messages on his BB from Jamster. They are similar to this:
Get new screensavers from Jamster. Your Big Plan credits have been renewed. ($1.99/week) Help:866-856-JAMS. Cancel.txtstopbig to 35555 T&CJamster.com

They are getting billed 1.99 for each message. Is this just SMS spam or did he sign up for something.

[xxhiyanxx]

jamster is a service that you send a text to and they send you a ring tone or a picture for a price... maybe he sent them a text thinking he'd get the ringtone and they signed him up for the service?