Hopefully the title of this blog has scared you into reading more and also testing in your own environment!
Today I was pulled into a support case where a client was testing 911 while switching sip providers, they discovered that the Skype for Business client was successful but the Polycom VVX would fail to make the all important call. Some more testing we found the VVX had no issues with other X11 calls like 411.
Time to trace… Look at that, the call from the VVX is sending “911” right to the Route and bypassing the Dial Plan normalization and getting rejected. “This user is not authorized to call the specified number or none of the routes have a valid gateway configured.”
Strange thing is I know 911 from the VVX worked before with this client. Nothing like spending a night testing firmware (http://support.polycom.com/PolycomService/support/us/support/voice/polycom_uc/polycom_uc_software_for_lync.html)…
Looks like a few have reported the issue but didn’t understand the cause:
A fellow colleague of mine, Korbyn has posted a similar article on 911: https://uccramblings.wordpress.com/2016/07/15/lync-skype-emergency-calling/