Another localized favorite, this site focuses on speed. You simply enter the recipient's number (starting with the local code like 03xx), type your message, and hit send. How to Send an SMS Online (Step-by-Step)
These websites are frequently used to send messages to Pakistan without requiring a user account: Send Free Sms Online Without Registration In Pakistan
Sites currently working in Pakistan (Check the latest status): Another localized favorite, this site focuses on speed