The description of ADL_STR_NO_STRING in adl_str.h (repeated verbatim in the ADL User Guide) is misleading:
ADL_STR_NO_STRING doesn’t really indicate that the string is not known - just that it’s not included in the “standard” strings.
eg, “+COPS:” would hardly be considered “unknown” in the literal sense, but it gets the ADL_STR_NO_STRING id! 
So why is “+COPS:” still not in the “standard” strings list?! 
Why isn’t there an equivalent of wm_strGetParameterString to extract the response names (like +COPS:) that aren’t included in the “standard” list?!
Personally I find it easier to just use custom functions that provides the same functionality but that you can extend on your own instead of relying on Wavecom…