I have an asterisk installation on an external IP, along with all the clients on external IPs, all routed through the same router on a /29 subnet which is then connected to an ADSL connection through another routed external /31 subnet. ie - I have 2 externally routed subnets, one for my connectivity, and one for my LAN. External lines are provided by Chan_Capi and 2 ISDN lines. Now the problem I'm having is that when the ADSL connection drops, the phones do not ring - the ISDN rings, but asterisk cannot appear to route the calls to the phones to make them ring. There are no DNS records used anywhere, purely IPs so external DNS lookups should not be necessary. All the /29 subnet IPs are in the arp cache of the router so there should be no need to go hunting outside of the LAN to route calls. Is this standard behaviour? Would i be better off natting all my phones and disabling can_reinvite and enabling use_nat I know asterisk can be used on internal IPs, but am a little confused as to why this setup fails when the ADSL is down. Any networking gurus out there who can advise?