Several web service firms piggyback the mobile carrier’s text-messaging networks. Using these services is as simple as sending a regular text message: In most cases, the user types out a request using the phone’s keypad and the service’s special code words. Then the user sends that message to a specified number. The service replies with the information the user asked for.
Example Google:
Searching from the phone is as simple as sending a text message to the number 466453 (that spells “GOOGLE” on most handsets), with one of Google’s keywords and the query. Google will reply with a set of results.
The service is especially useful when the user needs information related to where he is — he can just add a zip code to the query.
Sending “Pizza 90210,” for example, will return a list of pizza restaurants in Beverly Hills, with addresses and phone numbers. On most cell phones, the user can click the phone number to automatically dial.

