Send free text messages from a PC by linking a Google Voice and Google Hangouts account to send texts from the Hangouts interface; alternatively, use sites such as TextEm.net or OhDontForget.com as of 2015. Another option is to send the text as an email by using the recipient's phone number and the email address format for her carrier.
Google Voice offers free phone numbers through which you can make calls and send text messages over the Google Voice app on supporting smartphones. Link this account to a Google Hangouts account, which handles the company's text and video chatting service, to send texts through the messaging system. The linking process involves creating a Google Voice account through a Google account tied to Gmail.
TextEm.net offers a basic system wherein you enters the phone number and carrier of the recipient along with the message and an optional email address to send a single text. The service does not support conversation unless you create an account with the site.
OhDontForget.com offers a free Web group text messaging service that includes the option to message several people at once. You can schedule texts for future dates and times, and any replies appear for all text participants.
To send a text as an email, type the recipient's phone number in the To field of the email message, and add the specific domain for the carrier, such as @text.att.net for AT&T.