COM_RING()
 Queries the ring line
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 Syntax

     COM_RING(<nComPort>) --> lActiveRing

 Argument

     <nComPort>  Designates the port (1 to 4) on which the ring line is
     tested.

 Returns

     A return of .T. indicates that the ring line is active (MSR bit-7 = 1).
     A return of .F. indicates that the ring line is inactive (MSR bit-7 =
     0).

 Description

     COM_RING() lets you check the ring line of a port from within a program.

 Note

     .  When TERI (Trailing edge ring) is required, use the COM_MSR()
        function.

 Example

     Modems generally show the ring signal of an incoming call.  This does
     not mean that a trouble free connection has been established.

     DO WHILE .NOT. COM_RING(1)            // Wait for call (RING)
        * ...
     ENDDO

     ?  "Call detected..."