The Information Transfer Capability for the current
or last call.
unknown - If since system startup there has been no call
on this interface, this object has a value of
unknown(1).
speech - refers to a non-data connection
data56 - 56k data.
audio31 - audio 3.1 kHz; refers to data mode connections
audio7 - audio 7 kHz; refer to data mode connections;
'Unrestricted digital information with tones/
announcements'.
video - as defined in Q.931
fax - Facsimile
modem - V.3x modem