10.60.1. Feature Description 
The "User-to-User Service 1 Implicit" and "User-to-User Service 3"
services are available for basic S0 access. Both conform to protocol
requirements.
Applications for the UUS3 service are as yet unavailable. The UUS1
Implicit service, however, is supported by most ISDN terminals. It is
used to transmit brief texts, e.g. "Am on holiday".
Which type of User-to-User service (UUS) is used depends on the program
or terminal currently in use.
The following UUS are supported:
|
Service
|
supported
|
Effect on the connection
|
Effect on the application
|
|
UUS1i
|
yes
|
Although the remote system does not support
this service the connection is established.
|
Loss of comfort, depending on the application.
|
|
UUS1e
|
no
|
If this service is not supported by the remote
system the connection is not established.
|
No function
|
|
UUS2
|
no
|
The OpenScape 4000 rejects this service.
|
Connection is not established
|
|
UUS3 prefered
|
yes
|
Although the remote system does not support
this service the connection is established.
|
Loss of comfort, depending on the application.
|
|
UUS3 required
|
yes
|
If this service is not supported by the remote
system the connection is not established.
|
Connection is not established
|
The UUS differentiates between 'preferred' and 'required'.
Connections requiring 'UUS preferred' are usually established
even though the service might not be supported. On the other hand, connections
requiring 'UUS required' are not established if the service
is not available.
|
implicit
|
explicit
|
||
|
preferred
|
required
|
||
|
UUS1
|
not implemented
|
not implemented
|
|
|
UUS2
|
not applicable
|
not implemented
|
not implemented
|
|
UUS3
|
|||