A nice website, Degesms.com, allows you to send unlimited, anonymous messages (without disclosing your number) and free messages to any number in Pakistan and that too with 600 characters support. You don’t have to register for the site or any other service. Just visit their site and you can start sending messages.
You need to fill the above form in order to send messages in Pakistan. Just fill in your Nickname/Name (Any name will do) , Input the Receiver’s number, the Message you want to convey to the receiver, and finally the Security Code or usually called the CAPTCHA.