If you are still paying to send your friends text messages through your cell phone, you can do it for free by sending that same text message from your e-mail account. All you need to know is your friend's service provider.
Sign in to your email account and compose a new message.
Enter your friend's phone number and cell phone service provider address in the address field of your new email. For example, if your friend's phone number is 555-123-4567 and his cell phone service provider is Sprint, type in the address field: firstname.lastname@example.org.
Compose your text message in the message body field and "Send" your email.