Google filed a patent in February 2006 for a mobile payment system called "Gpay". The patent application describes a micro-payment system which allows consumers to pay for cheap products and services via SMS.
Some examples Google provided in the patent application:
For example the original payment message may include a store identifier (e.g., "gpay Starbucks357 3.50" or "gbuy McDonaldsFresno5 8.53") or the location may be implied, such as by determining the location of the device sending the payment request (e.g., for GPS-enabled devices).
For example, the user of device 14 may want to send twenty dollars to a friend whose mobile number is 850-555-1212. The user may thus type and send the following text message:  gpay 8505551212 20 to the Google text message address of GOOGL (46645), or to another address.
User1 may choose to pay multiple people using a single message. The syntax of the message sent by device 14 may permit for such payments, such as by stringing together multiple identification numbers. Thus, for example, where multiple vendors are sharing in a transaction, User 1 may divvy up the payment to them. As one example, where two vendors share a five dollar transaction 80/20, the message may take the form of:  gpay 8505551212#6123355070 4#1
Likewise, for transactions as part of a drive-through, a user may type:  gbuy inandout001 5.27 white Pontiac Bonneville