11-digit and 10-digit ELINs in CER

[Stephen Tomko]

Looking for some insight here. Our organization, for some time, has deployed 11-digit ELINs in CER for our Conventional ERLs to match our number 11-digit number plan (1-XXX-XXX-XXXX). We recently introduced Intrado ERLs to work with RedSky's E911 service. The ELINs associated with the ERLs are a mandated 10-digit (XXX-XXX-XXXX). When I say mandated, I mean CER won't allow an Intrado ERL to be configured with more than 10 digits.

This isn't particularly a problem for outbound calls as the Calling Party Mask for our Route Points can be manipulated to ensure the correct 10- or 11-digit ELIN is indicated. However, the problem is during PSAP call back. Our PSAP call back prefix is 913. The DN associated to the PSAP call back CTI Route Point is 913XXXXXXXXXXX (that's 11 X's).

This becomes a problem for several reasons

1. Since we are sending a 10-digit ELIN to the PSAP, the PSAP will call back using the 10-digit ELIN. Typically we would transform this into a +1-XXX-XXX-XXXX format, however, when that gets sent to CER, it will be unrecognized because, again, the Intrado ELINs are 10-digits.
   
2. We run into the inter-digit timeout if we transform using 913XXXXXXXXXX (that's 10 X's) as the DN associated with the CER CTI RP for PSAP call back has 11 X's
   

The only alternative I see is to change all ELINs, conventional and Intrado to 10-digits, have the PSAP callback prefix be 9131 and digit strip 9131.

Thoughts?

[Chris Deren]

You first need to translate the callback to prefix 913, so why not build specific TPs for the RedSky controlled ELINs and prefix 9131XXXXXXXXX, which will then match the common 913XXXXXXXXXXX CTI RP?

Chris

[Stephen Tomko]

Chris, first of all, thank you for your response. Since we have 11-digit dial plan, all calls coming in will ALWAYS be prefixed with a 1. PSAP call back on a number XXX-XXX-XXXX will eventually be identified in CUCM as 1-XXX-XXX-XXXX.

To your point, more exactly, CER restricts ELINs assigned to Intrado ERLs to 10 digit format only. If I have a 10-digit ELIN XXX-XXX-XXXX, but I send to CER 1-XXX-XXX-XXXX it won't match for PSAP call back.

[Chris Deren]

I see your point, how about trying to make the 913 RP as 913!, never tried it but might work.

If that does not work, I think the only other option would be to change your traditional ELINs to 10 digits as well :-(

Chris

[Stephen Tomko]

913! would assume that it'll accept any number. I'm afraid of interdigit timeout which is about 12-15 seconds for us.