"newbie" avaya S8700 to asterisk (trixbox V2.0) th

Happy new year to the Asterisk Community !
I’m looking for configuration and explanation to connect an Avaya S8700 (CM 1.3) to an asterisk box through H323 Trunk.
I need to call asterisk Sip extentions from avaya and avaya 4620 phone from asterisk.
Sorry for my english.
Thanks a lot for your help