When you call TSPI_lineGetDevCaps and pass it an instance of the structure,
the function may tell you that the block of memory you passed is too small.
That is, the explicit fields declared as being part of the structure are
just the 'header' part of the memory layout of the information.  After those
fields, there is an indeterminate amount of extra memory required for
things, like the name, which may vary in length.  The dwLineNameOffset field
of the structure tells you how many bytes into the structure the start of
the line name string is (it will begin after the last explicit field shown
in the structure declaration), and the dwLineNameSize field tells you how
many bytes of string data are stored there for the name.  To actually
extract that data, you'll need to get the bytes at that offset and for that
length from the structure and convert them to a string.

This is a case where representing the structure in memory as a byte array is
probably the best way to go.  That way, when you create it and call
TSPI_lineGetDevCaps and it returns an indication that there is not enough
space, you can internally extend the array and try again.  There are
numerous examples of this use-a-byte-array-as-a-structure-for-P/Invoke in
the OpenNetCF framework, as well as in the archives of this newsgroups.

Paul T.

I think you might find it easier to use a prebuilt wrapper.
Take a look at http://www.alexfeinman.com/downloads.asp?doc=tapi1.1.zip
If you decide to take a look at it, I would appreciate a feedback - I'm
trying to freeze the feature set so that a beta can be included into
OpenNETCF SDF