Major problem - local SIP phones & internet failure

I have recently found a major problem with a customers installation.
They have a setup with Zap trunks and a few Zap analog extensions (all on a TDM2400E) plus ten Polycoms (501 & 601) as the main phones.

They also have a couple of SIP trunks via an ADSL internet connection.

The ADSL connection went off for a few hours recently, and shortly after ALL the polycoms lost their registrations. The only working phones were the ones on the Zap channels.

The Polycoms were still working fine with DHCP & FTP from the asterisk machine, including logging boot attempts etc., but could not register with Asterisk.

Within minutes of the ADSL connection coming back online, all the phones registered and started working again.

I’ve since upgraded FreePBX to 2.3.0 and Asterisk to (from 1.2.x), but the situation is still the same - no Internet, no Polycoms…

I have no idea if this a bug in my setup or something in Asterisk / FreePBX, but I desparately need a cure…
Thanks for any info,

it’s a well known Asterisk issue, no DNS available - Asterisk freaks out, period. I believe if you use all IP addresses in your configurations in Asterisk (so trunk configs) it may solve the problem - otherwise, you are at its mercy. If you search the asterisk mailing lists, you’ll see it is all over. Another stop gap (very manual solution) that you can do in FreePBX 2.3 is go in and disable all VoIP trunks - since it has the same effect.

I remember seeing something about problems if there was no DNS available, so I have DNS running on both the asterisk machine and a data server on the site.

It sounds as if the problems actually occurs when asterisk fails to resolve a hostname, rather than when it fails to contact a DNS.
It could do with either a cache or something that returns a dummy or local IP when it fails to resolve the real address.

For now I’ll change to using the actual IPs, as you suggest.