For example, an AT&T subscriber whose phone number was 555-555-5555 would receive e-mails addressed to 5555555555@txt.att.net as text messages. Subscribers can easily reply to these SMS messages, and the SMS reply is sent back to the original email address. Sending email to SMS is free for the sender, but the recipient is subject to the standard delivery charges. Only the first 160 characters of an email message can be delivered to a phone, and only 160 characters can be sent from a phone. However, longer messages may be broken up into multiple texts, depending upon the telephone service provider.