Using pre-established connection

Pre-established connection makes it possible to connect to the meter without establishing the connection to the meter. This makes possible to read fast simple data from the meter when AARQ/AARE does not need to send. This might be very useful with slow data connections. It's possible that the meter is supporting multiple pre-established associations. The client address defines the used association and it's the same way with pre-established connections. Meters usually allow only simple data that fits into one message reading with pre-established connections. 

Note: All meters don't support pre-established connections.

Connection information is unknown

Because the client doesn't establish a connection to the meter, the connection information is not shared between the client and the meter. This means that the client must know what settings are used. For example, the conformance information is unknown. The client must know what conformance server is supporting. 
With pre-established connection, the authentication level is not available because it's not sent from the client. 
The connection may be unsecured, but usually secured connection is used with pre-established connections. With the secured connections the meter may define the client system title. The client system title can be read from Security Setup object. 
For example, the Italy standard UNI/TS 11291-11-2 defines that the system title is not sent with Glo ciphering messages and this causes that the client must use the same system title that the meter defines in Security Setup object. 
 

Association view

The association view is not always available for pre-established connections. This is for the security reasons. The client application must know what it can do with the the meter. 
This means that COSEM objects must be added manually.

Closing the connection

Because the connection is not established, it's not closed.