A system and method for enabling a user to invoke a service over a signaling channel in a communication system with a communication device such as a mobile phone. The user dials a series of digits into their phone and enters them into the disclosed system, for example by pressing the send key on a mobile phone. The digits entered by the user include a prefix or routing code, and a data code. The dialed digits are transferred to a call switching system, which determines, based on the prefix code, a processing system to which a message is sent. The processing system further determines, based on the data code of the dialed digits, the service to provide and how the service should be fulfilled. The service can be fulfilled by content over the signaling channel or a transport channel, or both.