Though it's becoming rarer to find yourself without a cellular signal, it occasionally does happen. If you're unable to use your cell phone, and you still need to send an SMS text message to a recipient using the AT&T, Verizon or T-Mobile carrier, you can send the message using your normal email service. This is possible due to what's called a gateway, which transfers text and email messages back and forth between the two networks. In most cases, the recipient will be able to reply to your email address via SMS message.
Open a new email message.
Enter the 10-digit cell phone number of the person to whom you want to send the message in the email message's "To" field. Depending on your email client or provider, the field might be called "Recipients."
Add the SMS gateway address of the recipient's cellular provider immediately after the 10-digit phone number. AT&T uses "@txt.att.net," Verizon uses "@vtext.com" and T-Mobile uses "@tmomail.net." For example, to send a message to an AT&T wireless customer, the address might look like "email@example.com."
Compose the message, keeping in mind the 160-character limit for SMS messages. Longer messages will be split into multiple parts and may not arrive correctly.
Send the message as you would any normal email.