SER to asterisk

SER sip express router and asterisk combination in the following way:
all users are connected and registered to SER, and sends every Invite packet to SER

SER is acting as a SIP registrar as well as call router, sooo as soon it recieves an invite message it forward it to the asterisk for call processing and creation.

all i want to do is to utiilize the true potiential of SER by maximizing the number of recieving calls, which only be possible if SER is able to forward the call to asterisk for its session creation and controling and other activities while removing itself from each particular call.

suggestions and solutions…???