How to Disable incoming Text Messages

[honeybrain]

By Mistaken i have registered my phone number with one of the website, who provided ringtones by that time. So now i am keep getting messages that is costing more dollars to my bill because i have no subscription for text messaging. Some times i am even receiving international text message. It's like $20 to $50 per month. I am in the process of negotiating with Sprint to get the service

Question: Is there any possibility that we can stop incoming text messages by any chance. Like i knew blocking calls from specific number. So i wanted to completely disable the messaging service on PPC 6700

Any help would be appreciated