[asterisk-users] Losing local SIP phones when internet goes down?

[Dana Harding]

> OK, I've now installed a local caching nameserver, but don't see any
> change at all.
> - Tested name resolution in general: working fine.
> - Turned ADSL router off and tried to make local and Zap calls: no luck.

Did you try to make any calls before pulling the plug on the ADSL router? 
dnsmasq wouldn't have had the chance to cache any lookups that are made if 
you didn't.

> - Rebooted machine and tried again: still no luck.
>
> Again, the logs indicate that Asterisk thinks the SIP phones are
> unreachable.
>
> Was there anything special I needed to do with the setup of dnsmasq, or
> its interface with Asterisk?  If not, I'm stuck again.

Turn on logging of dns queries in dnsmasq.   (-q or --log-queries).  That 
should
1) verify that it is actually being used for lookups
2) tell you what, exactly, it is being asked to resolve.  (which you could 
then add to your hosts file)