Asterisk Upper Registration Mode

Hello

Well I’m not too sure if this is the right section for this question or not… My question is I have one asterisk machine and one Soft switch VoipSwitch and I want my Asterisk to be placed before VoipSwitch working in Upper Registrartion mode…taking all request from my Linksys PAP2 and forwarding it to my VoipSwitch where all SIP accounts exits… Rightnow im doing the same through OpenSBC but wants to replace it with asterisk

Is this possible???