Int 14 Fn 03  - Connection Manager - Return Communication Port Status      [N]

   AH = 03h
   DX = FFFFh
   AL = connection ID

Return: AH = return code (00h-02h) (see #0229)
   BH = line status (see #0232)
   BL = modem status (see #0231) (only bits 4,5,7; all others zero)

Notes: if DX is 0-3 on entry, Connection Manager emulates the standard BIOS
     function, but redirects the port over the network; if DX is any other
     value, the call is chained

See Also: AH=00h/DX=FFFFh,AH=04h/DX=FFFFh,AH=0Ah/DX=FFFFh

Bitfields for Connection Manager line status:
Bit(s) Description (Table 0232)
 7 CTS changed
 6 current CTS state
 5 timeout
 4 break
 3 framing error
 2 parity error
 1 overrun
 0 current carrier state (0 active, 1 no carrier)