Several people have pointed me to a geekzone forum post involving Orcon back in Oct 2011 but the message that was being reported does NOT include the ‘alternative network’ bit. That message is in fact fairly common in VoIP systems.

On 12/02/2015, at 8:39 am, Glen Eustace wrote:

Both Spark and Vodafone have said that the exact wording and the voice are important in trying to identify where it is coming from. Neither of their teams recognise either :-(

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“Your alternative network call is unable to proceed at this time, please try again later”.The voice is a pleasant Kiwi (though I’m not a linguist so might not be) female.

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I was tempted to say something facetious about Spark, Vodafone and "thanks" in the same sentence together but it's good to hear they've worked out a possible explanation. Cheers for posting the update. - Damian On 17/02/15 07:44, Glen Eustace wrote:

Just a follow-up.

Spark and Vodafone now believe the issue is/has been congestion on the 06 inter-connect between the two telcos. In this situation, apparently calls have been being re-routed into Kordia’s network ( no idea where they end up but not where they were supposed to go ). Additional capacity is going to be being provisioned.

Intermittent telephony issues can be hard to troubleshoot in an enterprise, doing so on a carrier network is obviously even worse. So thanks Spark and Vodafone.

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On 12/02/2015, at 9:05 am, Glen Eustace mailto:geustace(a)godzone.net.nz> wrote:

Several people have pointed me to a geekzone forum post involving Orcon back in Oct 2011 but the message that was being reported does NOT include the ‘alternative network’ bit. That message is in fact fairly common in VoIP systems.

...

On 12/02/2015, at 8:39 am, Glen Eustace mailto:geustace(a)godzone.net.nz> wrote:

Both Spark and Vodafone have said that the exact wording and the voice are important in trying to identify where it is coming from. Neither of their teams recognise either :-(

...

...

“Your alternative network call is unable to proceed at this time, please try again later”.The voice is a pleasant Kiwi (though I’m not a linguist so might not be) female.