🚀 go-pugleaf

We have a cisco 4000 running IOS 10.3(6) which has an 8-port
BRI module. Originally we had three lines (2B+D) which forwarded
from one B-Channel to the other, so that anyone calling in would
get the first available channel. This was in operation for a couple
of months.

Next, we added three more lines (also 2B+D). We asked the phone
company to add these to our previous hunt group. After this was
done, the router stopped answering incoming calls altogether.
The phone company said that moving from three lines to six
required a different configuration.

We eventually found that, just by removing the LDN from the
isdn spid lines, things seemed to start working. We later found
out that the first B-Channels were answer calls, but the second
B-Channels of each line would reject them.

What changes do we need to make to stop rejecting the calls?
The switch is a 5ESS and is using National ISDN. The tech
support person at the phone company could connect to the first
BRI channel just fine, but got a "Not Endpoint Identified" error
and a protocol error when trying the second channel. We tried
three different values for the LDN on the second SPID: blank,
that line's actual LDN, and the LDN of the main number of the
hunt group.

Does ISDN call setup involve the router check some sort of field
which contains the expected LDN? If so, how can I find out
what it expects?

Thanks!
Steven R. Pfister // Network Administrator
optimum.net
srp685@optimum.net