Qualify failed while network down

Hello everybody:

The title is somewhat misleading. My asterisk box has three ‘remote’ and six in house peers. All in house peers are referenced by ip-number, though we have a local name server too.

We had an Internet failure yesterday and asterisk wasn’t able to ‘peer-poke’ FWD and broadvoice anymore (this is, of course, correct). However, asterisk was also unable to ‘peer-poke’ ANY internal peer (which are connected using SIPURA adapaters). So - pretty much the whole system was reported to be down.

However, I was able to ping all local clients, I checked them via web-interface and all reported (on the web-interface) to be registered.
I ssh’d to the asterisk box an ran all the tests (ping, wget …) from there, everything was ok. I finally had to change their ‘qualify’ setting to ‘no’ in order to be able to use the still working PSTN-gateway (via Sipura 3102).

Question 1)

What might be the reason that, during times of Internet outage, asterisk seems to be unable to peer-poke any internal sip client?

Question 2)

Is there a (simple config-) option to have asterisk to fall back to use a different peer in times of Internet outage? I.e. should the Internet not be available, route all outgoing calls through xxxx ?

Thanks for your ideas.