[Asterisk-Users] Re: failover (was Re: voicepulse)

[Matt Lawson]

> But this is not to say _you_ can't built a reliable VOIP based
> system.  Get _two_ providers and set up your dial plan in
> extensions.conf to "fail over" if one service fails to
> connect to dial via the next one and finally if both fail
> use pstn. your users will see a system the "just works".

Now there's an idea.  

I'm playing with this now, but there's at least 1 case I'm having 
trouble recognizing:

The call connects but then drops due to "unauthorized."  It then only 
goes to the "h" extension and I don't get a chance to try again.  Is 
there anyway to detect this?


I have to cover all of the following cases:


1.  VOIP IP address is not reachable.  Goes to extension n+101 (seems to 
work as expected)

2. VOIP service answers but refuses with call with "unauthorized".  It 
just goes to the "h" extension  Is there any watch to catch this 
failure?  Perhaps put a timer on it and say if the call was less than 5 
seconds or something try the next one?

Yes I am using a correct username and password and getting this today 
(not from Voicepulse, from another provider).  But there's also a 
moderate chance that during our systems' setup a name or password could 
be misspelled so I need to cover this case.

3.  VOIP service connects but reports "all busy."  Well this one is hard 
to test.  But I can make the Zap channel busy.  It goes to extension 
n+101 as expected, so I'll have to assume that a busy VOIP service does 
the same thing.

I was trying to determine if the "t" or "h" extension would be useful 
for these but I think not.  The timeout has to be set long enough for 
someone to actually answer (20-60 sec or whatever).  The "h" is always 
visited at the end of the call, whether it was sucessful or not.

Any other cases, or suggestions how to handle case #2?