Looking for some support

okay im new with asterisk, and fell into it when i was look for info about VoIP, well my questions is asterisk compatitable with the same setup at like Ventrilo? meaning codex like i know ventrilo is a gsm full rate, speex codex (ventrilo is another type of VoIP) so is asterisk a propretary voice over internet protocol and how can i get asterisk to connect to one-- if you think this doesnt make sense let me know so i can clear it up

Start reading:
downloads.oreilly.com/books/9780596510480.pdf
If you use CAPITAL letters in the begining of sentence, also dots and commas - you could get more answers.