This interface is crucial for enabling the exchange of MMS messages across different carriers. 

• Inter-Carrier Communication: MM4 is used for the transfer of MMS messages between carriers. This is important when the sender and the recipient of an MMS message are on different mobile networks.

• Based on SMTP Protocol: The MM4 interface typically uses SMTP (Simple Mail Transfer Protocol), which is the standard protocol for email transmission over the Internet. This allows for easier integration and compatibility with existing email systems.

• Format and Standards: Messages sent over MM4 are formatted according to specific standards, ensuring they can be understood and processed by the receiving carrier's MMS Center (MMSC).

• International MMS Exchange: MM4 plays a critical role in international MMS exchange, as it facilitates the sending of multimedia messages across borders and between different mobile service providers.

The MM4 interface is a key component of the MMS ecosystem, enabling seamless multimedia messaging across different networks and geographies, thereby enhancing the functionality and reach of MMS services.