Melbourne and Detroit emergency call centers simultaneously fail

A co-incidence that caught my eye this week was the failure of emergency call centers in Melbourne, Australia and Detroit, USA.

Melbourne's system failed at 19:00 local time on Friday, 5 July. Detroit's communications meltdown started at 05:00 local time on the same day. 19:00 - 05:00 = 14:00 hours, which is, co-incidentally, the difference in timezones between the two cities

Detroit's failure was slashdotted, Melbourne's was not. Were there other cities that experienced this same outage on Friday?

Just what could be going on then? Are they running their systems on a common cloud infrastructure that is not completely under the control of local technical staff? Was there an expired SSL certificate embedded in the application software, much like the certificate expiry that recently caused failure in Microsoft Azure?

Using free and open source software is a life or death issue

Are these systems based on free and open source software? Can the local authorities, their technical experts and auditors inspect the software to detect such issues ahead of time?

Closed, proprietary outsourced solutions often take significant control away from the users of technology.