RE: does emergency (911) dispatch uses IP ?

["Naslund, Steve" <SNaslund () medline com>]

So, to explain the whole system…..


1.      From your location to the your serving CO would be IP, POTS, Cellular however your normal phone call route.

2.      From your CO to the CO(s) serving your 911 center.  Might be a dedicated trunk or may have high priority to 
seize channels within the normal trunking between COs.  The transport being TDM or VOIP is up to the local carrier to 
decide.

3.     From the 911 center to the to the responders can vary by area and size.  Major metros can route to dispatch 
centers that handle police fire and other services and they can usually communicate over a dedicated trunked radio 
system through the area they cover to directly communicate with responders and command elements.  For a small town 
volunteer department the call might go to a county level dispatcher who pages out the responders.  It might even be 
ringing a single phone at the local PD.  It is up to each municipality to determine how they want the calls routed and 
the phone company assigns each number they assigned to a 911 center based on your street address.  There is a global 
table (used to be maintained by Bellcore, then Telcordia, I’m not sure now) that shows ranges of street addresses 
mapped to the correct 911 center that is used to populate the phone system.

4.       Large Metros and advanced 911 centers send voice and packet/cellular radio to responding units often giving 
them maps, aerial views, known hazmat on site, and other data.  If you have a large enterprise you can buy systems that 
allow you to communicate data like this from your organization to the 911 center.  My company has a data link that 
sends mapping data, entrance information, and even has our security people meet the responders at the door every time 
911 is called.   The wrong questions is IP or radio only, they are not mutually exclusive anymore.  A lot of these 
systems today are cellular data transmission or packet over radio.  Big county wide systems are often hybrids of both.  
They can have their own radios covering major population density and use cellular data to fill in the shadows in their 
coverage.  The radio user just sees the device as a walkie talkie and all that switching is transparent to them.

Steven Naslund
Chicago IL


> Guys,
> While reading CL network down impacting 911 services, was trying to get more information about how does this network 
> looks like. From end user to center, I guess VOIP is used. Wondering what is the communication method >from  Emergency 
> service center to end units (Police, Fire or any other services). Do they also use IP ? or its Still Radio only ?  if 
> it is IP, do they use Unicast or multicast or broadcast ?
>
> Tried googling, but did not get much information. Any insight would be appreciated.
>
> Thanks
> Mankamana