INT 6B - NPC NCSI EXTENDED SERIAL I/O - VIRTUAL CIRCUIT STATUS                  
	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
SeeAlso: AH=10h,AH=15h,AH=1Ah,AH=1Bh,AH=1Fh