You must know your recipient's cellphone provider to send a text message via your Hotmail account successfully. This is important because each cell phone provider uses a unique SMS Gateway. An SMS gateway allows you to use a specific e-mail address to send text messages on a carrier's network. This e-mail address varies from carrier to another. Text messages sent through your Hotmail account must still adhere to your recipient's carrier's character limit. Typically, most, if not all, cellphone providers have a 160-character limit for text messages.
Sign in to your Windows Live Hotmail account by typing your e-mail address and password in the "Windows Live ID" and "Password" boxes, respectively and then selecting "Sign In."
Click on the "New" link located to the right of "Hotmail." The Compose window opens.
Type your text message in the blank area and then enter your recipient's carrier's SMS gateway in the "To" field. Enter email@example.com (for example, firstname.lastname@example.org) if your recipient uses Verizon Wireless, 10-digit phone email@example.com if he/she uses T-Mobile, or 10-digit phone firstname.lastname@example.org if your contact uses AT&T.
Send the email as a text message by clicking the "Send" link. You have sent a text message via your account successfully.