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C613-16030-00 REV B
zThere is an ISDN call definition on the receiving router that will accept the incoming
call, but there is not yet a Layer 2 interface (PPP or Frame Relay) configured to use this
call definition.
zThere is an ISDN call definition on the receiving router that will accept the incoming
call, and there is a Layer 2 interface configured over the call definition, but this
particular call definition is already taken by another incoming call.
Once you have tracked down where the configuration error lies, and remedied the problem,
the ISDN calls ought to connect correctly.
Other tips for testing ISDN connections

If pings won't bring up a call, try activating it manually.

Typically when setting up an ISDN connection, you'll configure an ISDN call definition, then
configure a dial-on-demand PPP interface over the call definition, and then assign an IP (or
IPX, AppleTalk) address to the PPP interface. Then, the normal first step to testing the setup
is to try pinging the device at the other end of the link. If there is no response to pings, you
could go through all three steps above to try and determine why its not working. However,
you can possibly bypass some of the process by trying to 'manually activate' the ISDN call,
rather than trying to bring it up using pings. This is a more direct approach to testing the
ISDN connection, and can often give you more insight into what is going on.
The command to activate an ISDN call is:
activate isdn call=call-name
This command informs the ISDN module to directly attempt a call setup. However, before
the call setup is attempted, the router checks whether there is a Layer 2 interface configured
over the call, and if so, whether that interface is currently active. If there is no Layer 2 (PPP or
FR) interface configured over the call, then you will receive the error message:
Call has no user attached
If you receive this message, then carefully check the PPP or FR interface that you have
configured over the ISDN call. The commands show ppp or show fr will show which ISDN
call the router believes the Layer 2 interface to be configured over as shown in the following
figure for interface ppp4.
Check carefully that the name of the ISDN call reported by show ppp or show fr is exactly
the same as the name of the call you are trying to activate. Note that the call name is just the
string that appears after the "isdn-" in the Over column.
Name Enabled ifIndex Over CP State
-----------------------------------------------------------------------------
ppp4 YES 08 IPCP CLOSED
isdn-ntdial LCP STARTING
-----------------------------------------------------------------------------