In order to troubleshoot/debug/capture a scenario, debug_uri allows to define a list of subscribers/aliases that will be matched against From/To headers for every SIP message on a specific lb node. If matched that SIP message will be delivered to the assigned proxy node. In summary, any call to/from that subscriber will be easily traced since no calls are delivered by default to an inactive node.

To enable the feature, execute:

ngcpcfg set /etc/ngcp-config/config.yml kamailio.lb.debug_uri.enable=yes
ngcpcfg apply 'enable debug_uri'
ngcpcfg push-parallel all

There’s a command line tool available to manage the subscriber list. An example of use:

ngcp-debug-subscriber --resolve add lb01 +4310001000@example.org sipuser@example.org prx99
ngcp-debug-subscriber --resolve delete lb01 +4310001000@example.org
ngcp-debug-subscriber --resolve list lb01

Be aware that the list belongs to just one lb pair, the info is kept in REDIS local so list’s contents will survive lb restarts and switch overs.