Oh, I see. CCXML is a proposed telephony control language for voice
browsers, intended to describe the state machine of a voice application.
A websearch on "ccxml and c++" finds mention of code available from
Voxeo and Phonologies, plus other discussions.
As far as I can tell CCXML seems to have nothing to do with VOIP per se,
except that the audio channel it's intended to control might be VOIP-based.
Note also that CCXML is still in Working Draft status, which means it's
potentially subject to rapid change or to being discarded entirely if
folks decide it wasn't what they needed after all.
I haven't had any reason to investigate this, so I can't help you beyond
that. You might want to check telephony-specific discussions, as they
might have had more active interest in this particular application of XML.