Types of SMS:

1. Person to person (P2P) : chatting
2. Application/Advertiser to person (A2P): used for the purpose of advertising
3. Person to Network (P2N) or Person to Application (P2A): used when the subscribers send an SMS in order to access different kind of services
4. Internet to Person (I2P): sending an SMS from a web-page accepted by the operator.
5. Machine to Machine (M2M): a device that captures information and sends it to another device or a server