[Serusers] Can 'avp_check' check whether sourceIP and destinationIP are the same subnet segment?

If 2 UAs exist on the same network segment, e.g., 192.168.0.1 and 192.168.0.2, how to check whether sourceIP and destinationIP are the same subnet segment using avpops module? If 'ser' sits on 192.168.100.1, UA1 can send 'INVITE' then UA2 rings, but when we pick up UA2's handset, these two UAs goes to a panic. I have to reboot two UAs. So, I would like to 'rewritehostport' INVITE packets to 'man-in-the-middle-sip-server', 'asterisk' when UA1 INVITEs UA2. ser asterisk |.1 |.2 192.168.100.0/24 -------------------------------- |.254 router |.254 192.168.0.0/24 --------------------------------- |.1 |.2 UA1 UA2 Regards, Zen