You might be a little confused between sub and function. You can use call for both - but for function it makes no sense because you are returning a value (by using call - you are discarding the return value, so use a sub).
So you might have the following:
strReturn = adHandleQuotes... in your main code.
If you are not returning a true value and just modifying the value using byVal then use sub - not function.
FYI - The call statement only exists to support (much) older versions.