Types of SMS Service > Lookup
In a lookup service, the user initiates the SMS conversation. For example:
Send "Define <word>" to 46645 (GOOGL) or 95482 (WLIVE) and you will receive an SMS response with the word's definition.
Send a book's ISBN number to TicTap at 763-807-3927 to find out how much it costs on http://Amazon.com.
Lookup services have an added requirement beyond those of a notification service: you have to be able to send them a text message, not just receive one (making the email to SMS gateway implementation described later inappropriate). They are otherwise as straightforward to create as a notification service: take text input, parse, process, and respond via text.