An aggregator is an individual who owns an application hosted on their personal server; an aggregator provide the service of Re-selling and SMPP service. An aggregator working as a super admin and control and manage their client as per their services. Aggregators are only using different SMPP Accounts like Vodafone, Airtel, and Idea etc.
SMPP 3.3 the oldest used version (despite of its limitations, it is still widely used); supports GSM only.
SMPP 3.4 adds Tag-Length-Value (TLV) parameters, support of non-GSM SMS technologies and the transceiver support (single connections that can send and receive messages).
SMPP 5.0 is the latest version of SMPP; adds support for cell broadcasting.