The best and most secure way to block some one's cell number from calling you or messaging you is to report it to your service provider to see if they will do this for you but you will need to show them evidence like sms or call recordings.
I don't think you can block texting, but if you can call Sprint or Verizon or whatever[:
Ummm... You have 2 call the service provider but you have 2 b the account holder!! My mom blocked my txting 2!! It sucks!!
You unblock texting on your phone the same way as when or if your Dad blocked it. Seesee
To all people whos texting has been blocked you can still text I found out how wen my gf was spam textin me ok this can not be done if you or the person you wana text have a black berry ok its simple just text 165 digits (no spaces) then go to options and copy text highlite all 165 digits thn ok to copy then text what you wana say to the person and send itll say it didnt send but (it really did) thats the easy part now you need to get who ever you wana text to do the exact same thing or else you wont recieve it...