Understanding call flow in CER

Answered Question
Feb 4th, 2007

I'm having trouble understanding the call flow from callmanager back to CER.

When someoune dials 911 they hit a translation pattern that only has access to the E911 partition. This then hits a CTI route point of 911. This talks JTAPI to CER which in turn decides what route pattern based on switchport it will hit in the E911 partition such as 99.911. This will tell the call which specific gateway to go out of to hit the local PSAP.

This is where it gets confusing for me. When the PSAP needs to call the person back that dialed the number this must hit my gateway which in turn has access to the E911 partition. I'm assuming that the translation pattern 913XXXXXXXXXX sends this back to CER somehow. which then translates the calling number at this point back to it's original and then sends it out one of the CTI ports to the phone.

Please if someone can explain this process I would really appreciate I don't understand the 913XXXXXXXXXX translation pattern the most. Any insight is appreciated. Thanks

I have this problem too.
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Correct Answer by Chris Deren about 9 years 7 months ago

You are on the right track, the 913XXXXXXXXXX is used for PSAP callback, but it could be whatever you define it as.

Consider an example where one of your ERL has an ELIN of 312-555-2000, and a user has dialed 911, for some reason got disconnected, and the PSAP needs to call back:

1. 911 operator dials 312-555-2000

2. Call arrives at GW

3. Assuming 4 significant digits, there is a Translation pattern of 2000 (could be 20XX, or wahtever to match all of your ELINs) which bascailly intercepts this call

4. this TP prefixes 913 to the called number

5. The CTI RP of 913XXXXXXXXXX is matched and since it's controlled by CER the call is redirected

6. CER maintains the ELIN-calling phone relationoship for up to 3 hours, so even though the ELIN is different than the phone's DID the call gets delivered to the phone

HTH, please rate all posts!

Chris

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Correct Answer
Chris Deren Mon, 02/05/2007 - 06:50

You are on the right track, the 913XXXXXXXXXX is used for PSAP callback, but it could be whatever you define it as.

Consider an example where one of your ERL has an ELIN of 312-555-2000, and a user has dialed 911, for some reason got disconnected, and the PSAP needs to call back:

1. 911 operator dials 312-555-2000

2. Call arrives at GW

3. Assuming 4 significant digits, there is a Translation pattern of 2000 (could be 20XX, or wahtever to match all of your ELINs) which bascailly intercepts this call

4. this TP prefixes 913 to the called number

5. The CTI RP of 913XXXXXXXXXX is matched and since it's controlled by CER the call is redirected

6. CER maintains the ELIN-calling phone relationoship for up to 3 hours, so even though the ELIN is different than the phone's DID the call gets delivered to the phone

HTH, please rate all posts!

Chris

jason-calbert_2 Mon, 02/05/2007 - 11:58

Chris,

Thanks this is the best I have heard this explained. Appreciate the help

Jason

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