Internet down, Asterisk works

I have started and seen many posts on this and other forums regarding key parts of an Asterisk based phone system not working when the internet connection is down. For instance see … extensions

We are a business which never closes. We receive about 20,000 minutes per month of phone calls. 90% of the traffic is thru Vitelity and Voicepulse sip voip. If the internet is down calls failover to our pots lines.

Under no circumstances could we keep a phone system which breaks when the internet is down. As much as I like Asterisk and Freepbx, staying in business is more important.

I have eliminated the problem on our systems.

I use Debian Etch + Asterisk source from … ent.tar.gz and Freepbx.

When the net goes down I can

1- call another internal extension

2- call out using POTS

3- receive calls using POTS.

I use Debian. [in my opinion it is the most reliable Linux distribution. Reliable in that it never changes my system configuration without my knowing. ]

We have 3 outbound trunks.

Our outbound route is :
The 1-st is Vitelity voip.
The 2-nd is ZAP
3-rd VOIP

When the net is not working the call tries to go out through VOIP , times out then uses ZAP.

We have an outbound route set so when a call is prefixed with a 5 , the call will go out on the ZAP trunk.

I have kept extensive notes on how these systems were setup. In case the information could be of use to others I’ll post the page to a public wiki.

If you have questions on how to use Asterisk or Freepbx on Debian or keeping a system up when the net is down then respond to this .


The main reason and the much documented one for system failings when the internet connection is down is due to a couple of things.

1 External Sip peers cannot register as the link is down and the sip.conf is incorrectly setup and allows peers to register infinite times, this should be set to 4 or 5 times then give up

2 The link is up but DNS is down. causes the same symptoms as above and again the peer show have a limit on the number of re registrations and Local DNS backup should be in place such as hosts or a local DNS server.

Its good that you have got a reliable setup and to be honest so have the vast majority of sytems, forum can give a slanted view as they contain in the main users with posting problems not the users with no problems.

It great that you have posted a solution, I would encorage you to set up a wiki and add all your info so others can see it, Looking at the stats of my wiki which stands at just over 800 pages and has had over 65000 visitors so hopefully it has been of help to a few of them.


could you tell me your wiki address?

Hi Rob.

I’m also interested to see your setup notes.

can you also include some details of your hardwares.



my notes on the wiki are very specific to our setup. it refers to scripts and other pages which I need to make available…

our hardware is a Supermicro motherboard, 2-core Xeon , redundant power supply, 3-ware sata raid.
we have a Sangoma a-200 with 4 pots lines attached.

this is the link to the wiki page. … anAsterisk

the wiki refers to pages which I need to open to public and files I could attach.
but it is a detailed set of notes from a few Asterisk installs on Debian Etch. … nesys-2009