ISO/IEC 20115:2004 specifies the combination of base standards, together with the selection of appropriate options and parameter values, necessary to specify how QSIG/PSS1 can be used for Message Centre Access (MCA) procedures.
ISO/IEC 20115:2004 identifies the necessary or optional employment of particular functions, procedures and services for a
- Calling User to deposit messages for a Served User at a Message Centre,
- Served User to monitor the Served User's Mailbox for new messages,
- Served User to browse through the messages saved in the Served User's Mailbox,
- Served User to retrieve the messages saved in the Served User's Mailbox, and
- Served User to get connected to the Originator of a message or any other destination.