[Users] sl_send_reply with avp parameter

Hi, I was wondering if it's possible to create an openser script to automatically send an error response when an INVITE request for a specific SIP URI is received. For example, an INVITE to "sip:e403@domain" would return a 403 response, and requests to "sip:eXYZ@domain.com" would return a XYZ response. I've tried using avp: # get username avp_printf ( "$avp(i:2)", "$oU" ); # get error code avp_subst ("$avp(i:2)", "/e*/\1/" ); # send reply sl_send_reply ( "$avp(i:2)", "Error" ); But apparently it's not allowed to pass an avp parameter to the sl_send_reply function. Is there another way to accomplish this? kind regards, Sigrid Thijs