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Explorer

911 Call Handling

Let's assume that I have a network where every site has its own PSTN connections, and it's common for certain users to move from site to site via Extension Mobility. Is it necessary to buy the Cisco Emergency Responder application to handle this, or would that only be necessary if our sites did not have their own PSTN connections?

Another way to ask this say question: is it possible to force all 911 calls from all sites to use their own local PSTN connections?

1 ACCEPTED SOLUTION

Accepted Solutions
Collaborator

Re: 911 Call Handling

Yes. This is controlled by the calling search space assigned to the phone/line. If you plan on deploying Extension Mobility you will want to go with the CSS vs. Line approach. Basically you allow ALL calls on the phone but then BLOCK on the line calling search space.

When you assign a CSS (calling search space) to a phone AND a line the effective calling search space is a concatenation of the two BUT the line CSS takes precedence. Therefore, if you ALLOW all calls on the phone and then block Local, LD, and International on the line the effective CSS will be calling internal and 911.

With extension mobility you will define the phones CSS to allow all and then the users device profile you will define their effective css (BlockLocal, BlockLD, etc).

The phones CSS is what tells the phones which route patterns to use for gateway selection. Therefore, when someone logs in via extension mobility their ALLOWED calls (route patterns that are NOT blocked on the phone CSS) are routed out the local gateway.

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a0080447504.html#wp1044961

andy - berbee

View solution in original post

4 REPLIES 4
Collaborator

Re: 911 Call Handling

Yes. This is controlled by the calling search space assigned to the phone/line. If you plan on deploying Extension Mobility you will want to go with the CSS vs. Line approach. Basically you allow ALL calls on the phone but then BLOCK on the line calling search space.

When you assign a CSS (calling search space) to a phone AND a line the effective calling search space is a concatenation of the two BUT the line CSS takes precedence. Therefore, if you ALLOW all calls on the phone and then block Local, LD, and International on the line the effective CSS will be calling internal and 911.

With extension mobility you will define the phones CSS to allow all and then the users device profile you will define their effective css (BlockLocal, BlockLD, etc).

The phones CSS is what tells the phones which route patterns to use for gateway selection. Therefore, when someone logs in via extension mobility their ALLOWED calls (route patterns that are NOT blocked on the phone CSS) are routed out the local gateway.

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_implementation_design_guide_chapter09186a0080447504.html#wp1044961

andy - berbee

View solution in original post

Explorer

Re: 911 Call Handling

That sounds complex but I'm sure I'll get used to it once I understand how Calling Search Spaces and partitions work.

The good news is that it's possible to do it without buying yet another server and yet another application. :)

Highlighted
Explorer

Re: 911 Call Handling

Okay, that's going to work for almost all of our sites. However, we have a handful of sites that do not have their own PSTN trunks. They hop on a T1 tie line to another site that has PSTN trunks.

Can we set this up so that 911 calls from one of those sites will take an IP path to their "sister" site and then use those PSTN trunks? If so, can we ensure that the correct site information is presented to the PSTN?

Thanks!

Collaborator

Re: 911 Call Handling

For those sites I would recommend having atleast 1 or 2 POST lines into FXO ports on the router to send 911 calls out. You can send all other calls over the WAN/T1 but to be compliant you will need atlease one local CO line.

andy - berbee

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