[bars] ***SPAM*** Re: 911 outage root cause revealed

[Verhulst]

>     Interesting... If one can take the report at face value they
>     mention that the 911 centers could see the phone number of the
>     caller and then was able to call them back.   Assuming this is a
>     VoIP system, honestly what phone system isn't these days, this
>     tells me that the SIP traffic was making it through but the audio
>     data was not. These are typically carried on different network
>     ports and require specific firewall rules to allow them through. 
>     There is a common problem with VoIP system refereed to as 'one-way
>     audio' in which the calls are connected but only one of the
>     parties can hear the other.  This situation is almost always
>     caused by a misconfiguration of a firewall.  It could also have
>     been a defense mechanism whereby some firewalls can block specific
>     ports if it sees 'unusual' activity on a port.
>
>     If this was the case no amount of redundancy/failover would have
>     helped - the system wasn't down, calls were still going through.
>

FWIW, I was a principal software engineer at Oracle for 15 3/4 years. If 
your business is airline reservations or online sales (amazon) or yes, 
911 centers etc, you can't lose a single transaction.... ever. Your 
computers can crash or one of your data centers can literally burn to 
the ground and you just keep going. We know how to do this.

73s, Tony, W1DYS
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