I also found solution to another common feature I was planning to add: call screening (screening of calls with unknown/missing CID or from numbers I don't know or have placed in a special group) - in Asterisk this is a bit limited to about 2, 3 options which I have no control over, but in FreeSWITCH, it seems, I have a complete freedom of how/what to do when call screening is initiated - http://wiki.freeswitch.org/wiki/Dialplan_XML (Example 13) is exactly what I needed, though I take it I could customise it a bit so that:
I (as the called party) have the option (by pressing a specific key after receiving the caller's name) to: 1) accept the call; 2) send a message back to the caller saying this number is unavailable and then terminate his/her call; 3) redirect him/her to voicemail; 4) drop the call entirely without giving any explanation at all (or, alternatively, torture them with some moh if they appear to be telemarketing group for example). By reading that example, it looks as though this can be achieved.
If you only need "answer or reject to continue with the dialplan" then
simply use the pre-built Answer Confirmation: http://wiki.freeswitch.org/wiki/Freeswitch_IVR_Originate#Answer_confirmation Anything else will be a bit more complicated. For telemarketers, you could bridge them to http://itslenny.com/
One other thing: in Asterisk, there is a vast sound library for various messages/music/media which could be used. Is there a similar thing in FreeSWITCH or should I use Asterisk's media pack for now?
When installing if you did "make sounds-install" you got the basic sound package which is quite extensive. I recommend looking at the docs/phrase/phrase_en.xml and see the list of the phrases / pre-recorded sound files under the name "callie". -Avi