How to transfert the call to another server?

hi all
i have to asterisk servers :
i want that if someone call the first server, he get the girl of a2billing , who tell him to enter his code, … it is already done!
I want also if someone call the second server with a predifine number , the second server redirect the call to the first server and there he get the girl …

do you have any ideas ?

do it with the IAX2 protocol

exten => s,2,DIAL(IAX2/user:secret@remoteserver/${EXTEN},50,tr)

works great to me