SMS Short Codes
Short codes, or short numbers, are short digit sequences, significantly shorter than telephone numbers, that are used to address messages in the Multimedia Messaging System (MMS) and short message service (SMS) systems of mobile network operators. In addition to messaging, they may be used in abbreviated dialing.
Application-To-Person (A2P) SMS
A2P is delivered through Mobile SMS carriers/gateways. While SMS reached its popularity as a person-to-person (P2P) messaging, another type of SMS is growing fast: application-to-person (A2P) messaging.