SMS messaging technology can be used as the underlying communication medium between wireless devices and servers in a two-way interactive text messaging application. For example, search engines are two-way interactive text messaging applications. Let's say there is a dictionary search engine that supports queries in SMS text messages. It may operate like this:
- To find out the meaning of the term "SMS text messaging", you can type "find: SMS text messaging" in an SMS text message and send it to the search engine's phone number. After receiving your SMS text message, the search engine parses it and finds that it begins with the command "find" and follows by the words "SMS text messaging". The search engine then knows you want to find out the meaning of the term "SMS text messaging". So, it sends a text message, which contains the meaning of the term "SMS text messaging", back to your mobile phone.
- If the search result is very long and it cannot contain within a single SMS text message, the search engine adds "Page 1 of 2", "Page 1 of 3", etc, at the end of the reply SMS text message. The search engine also creates a session using your mobile phone number as the session ID and stores the term that you searched for (i.e. "SMS text messaging") in the session object.
- To request the second page, you can send a text message with the content "page: 2" to the search engine's phone number. After receiving your SMS text message, the search engine parses it and finds that it begins with the command "page" and follows by "2". The search engine then knows you want the second page of the search result. It retrieves the term that you searched for last time from the session object and finds that it is "SMS text messaging". The search engine then sends a text message that contains the second page of the search result for the term "SMS text messaging" back to your mobile phone.
Many other two-way interactive text messaging applications can be built using a similar way. For example, a company may want to build an SMS messaging application to enable its employees to query the corporate database while they are working outdoors.
