SMTP stands for Simple Mail Transport Protocol, an email protocol supported by many wireless and telecom providers.
Many telecom providers support SMTP, which is the industry standard email protocol. Keep in mind however, that the protocol l was not initially designed for text messaging, so the protocol itself lacks some of the structure found in other messaging protocols, making SMTP a less reliable method of sending messages.
In order to send a text message using SMTP, two pieces of information are required. The first required piece of information is the email gateway/format of the telecom provider that the wireless devices is associated with. The second required piece of information is mobile phone number you wish to send the message to.