There appears to be a big misunderstanding because ETI is commonly used in DAB+ for the “MUX to station” connection. There are major differences between ETI interfaces, which is why it usually has a suffix because only then do you specify the correct interface. ETI thus should be viewed as a general interface that is not further defined.
We briefly describe the different suffixes:
ETI-LI
LI refers to “Logical Interface”. This is actually the arrangement of the bits in an ETI frame i.e. the software data to be sent to the transmitter.
The following ETI interfaces package the ETI-LI to send over data lines/networks.
ETI-NI (G.703)
This type of interface uses the entire frame (32 slots) as a raw container for a serial transmission rate of 2048 kbps (E1).
ETI-NA (G.704)
Is slightly more complex because the header (slot 0) is used for link supervision and (slot 16) is used for telephone signaling, because of this 2 of the 32 slots cannot be used for data trasport. So the speed is reduced to 30 times 64kbps or 1920 kbps (E1).
Is a special format to send ETI-LI over IP networks (e.g. public Internet or private Internet). It specifies how the data in the ETI frame is converted into Internet packets (special protocol, also used in Digital Radio Mondial or DRM on the AM band).