The Information Transfer Capability for the current
or last call.
speech(2) refers to a non-data connection, whereas
audio31(6) and audio7(7) refer to data mode connections.
Note that Q.931, chapter 4.5.5, originally defined
audio7(7) as '7 kHz audio' and now defines it as
'Unrestricted digital information with tones/
announcements'.
If since system startup there has been no call on this
interface, this object has a value of unknown(1).