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New Member

E911 for multiple sites using PRI T1s on a 6608 blade

Hi all,

Ok, I'm having a bit of trouble getting E911 working and I need a sanity check.

We have a central processing setup with 2 PRIs at the central site. Each of the 23 remote sites has 2 analog trunk lines. We have a DID on the PRI for each remote site. Outbound calls for each site are sent through the PRI first and we've created individual route patterns for every site and specified a calling party transform mask for each similar to 5055991111 (different for each site) (not the actual number). When we call a normal phone or cell phone, the callerID info displays properly. It shows the correct info as we programmed it.

We did the exact same setup for each of the route patterns for 911 purposes. However, when we test the 911 calls, the 911 operator only sees the first DID number on the trunk 5055991100. It's almost like the switch isn't believing the info we're providing so it takes the default info.

We have the 911 route patterns setup to try the local analog trunks for each site first, but since there are only two and they will almost certainly be busy, so we need the PRIs to work with 911.

I'm hoping we don't have to purchase Emergency Responder to get this to work. I seems like it adds a bunch of advanced features, but I would think we should be able to the basic config manually.

We've contacted the Telco and they are saying its a programming issue on our side. Could be, but I'm confused why it works for normal calls and not for 911.

Thanks again for your help.


New Member

Re: E911 for multiple sites using PRI T1s on a 6608 blade

Has anyone been successful doing E911 out a PRI for multiple sites without purchasing Emergency Responder?



New Member

Re: E911 for multiple sites using PRI T1s on a 6608 blade

- We have found it useful to dedicate an analog trunk to 911 usage at

remote sites, so the concern that the analog trunk is unavailable is


However, you should reverify with your LEC that they are not masking or

rewriting the ELIN that has been mapped to your PRI's. You normally

have to tell them during provisioning that you want to control this (which

is accomplished using calling party transform masks).

A question back to you though is how are you accomplishing routing to

the correct PSAP for 911 services per remote location when a 911 call

uses the central site PRI versus the remote location analog trunk?

Are these sites all on the same campus so this point is moot? Or are

they in different geographies?

--- ----- ---

New Member

Re: E911 for multiple sites using PRI T1s on a 6608 blade

Hello, thanks for the response.

We're hoping we don't have to provision a dedicated trunk at every location...that would make a pretty serious dent in the cost justification for the Centralized call processing system at about $1000 extra per month.

As for the LEC overwriting the ELIN, that's what I suspect.

Question: Does the CO Switch distinguish between whether to overwrite ANI verus ELIN, or are they really just the same thing? When we modify the calling party transform mask for a regular route pattern using the PRI, it works as expected...just not the 911 stuff.

As for the question about how we're routing to the correct PSAP..I don't know. I thought that was built into the ELIN when the ALI database was checked? All of these locations are in the same city. Its a pretty small city, so I'm pretty sure they all have the same PSAP.

Thanks again, I really appreciate the help!


New Member

Re: E911 for multiple sites using PRI T1s on a 6608 blade

You won't need an trunk at each site, you said you have an analog line at each site, correct? Use the analog at each site for 911. I am in the process of installing a large central-Call manager installation. At each of the 25+ sites we installed a 1751-v with a 2-fxo. The 1751 does SRST and acts as the local gateway for all of the calls (the sites are small) but more importantly, they are ALWAYS the gateway for 911 calls. That way we know for sure that the 911 operators get the right info, and is the wan is down they can still make 911 calls.

New Member

Re: E911 for multiple sites using PRI T1s on a 6608 blade

Yes, I realize all of that, except I can't trust that those lines will not be busy. Each site currently has their main incoming number as the first analog line at each site. There's a hunt group which rolls the call to the second analog at each site, and then it rolls to the site's DID on the PRI.

We've decided to use the Analog lines in this fashion so the schools will continue to receive calls if they are in fallback mode.

Since all of the sites incoming calls are going to be coming through those analog lines first, I believe there is a very good chance that those analog lines will be busy when a user dials 911. The 911 Route List for each site is setup to try the local analog gateway first, and if its busy, forward out the PRI.

I could remove the PRI from the RL, that would ensure the call always gets routed out the analog interface, but more than likely it would ensure the user gets a busy signal when they dial 911....

I thought one of the biggest advantages of PRI was its ability to update the ALI and ELIN information..?

Thanks again,


New Member

Re: E911 for multiple sites using PRI T1s on a 6608 blade

Just FYI:

I finally got this working. Finally complained long enough and loud enough to get the telco to respond. Within 5 minutes of finally getting the *right* person on the phone, he recognized that the switch was configured to overwrite the calling party information on 911 calls. He flipped a switch and within a few minutes everything was working beautifully.

Thanks again for the help.