SMPP (Short Message Peer-to-Peer Protocol)
The protocol defines the information that needs to be exchanged between the user and the SMSC and the operations associated with the exchange of SMS messages. It can receive delivery reports for each message, so you can know the status for each SMS you send, automatically. Connection between client and server is always opened and checked periodically by client.
The primary use of SMPP is to send and receive medium-to-high volumes of SMS texts. It is often used by third parties (e.g., value-added service providers like news organisations) to submit messages, often in bulk, but it may be used for SMS peering as well.
There are different levels in bulk SMS marketing in that this SMPP protocol is used by an aggregator. Aggregators are persons who buy SMS directly from a provider and have full control to their SMS panel. They can create unlimited resellers and they can tie up with a number of SMS providers.
SMPP is no longer the sole means of delivering bulk SMS messaging. Similar throughput levels can be achieved by using multi-threaded http connections between peers.