Int 6B Fn 12  - Npc Ncsi Extended Serial I/o - Virtual Circuit Status      [S]

   AH = 12h
   AL = virtual circuit number (0-8)

Return: CF clear if successful
       AL = virtual circuit number
       CL = virtual circuit's state
       00h idle
       01h Telnet session, in command state
       02h Telnet session, connected to host
       03h-06h ??? (not returned by TelAPI)
   CF set on error
       AL = error code
       E2h invalid virtual circuit number
       E4h specified virtual circuit not allocated

Note:  this function is also supported by TelAPI

See Also: AH=10h,AH=15h,AH=1Ah,AH=1Bh,AH=1Fh