>>> import dbus
>>> bus = dbus.SessionBus ()
>>> bus.start_service_by_name ('net.ekiga.instance')
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/lib/python2.4/site-packages/dbus/_dbus.py", line 241, in
start_service_by_name
return dbus_bindings.bus_start_service_by_name(self._connection,
named_service)
File "dbus_bindings.pyx", line 1740, in
dbus_bindings.bus_start_service_by_name
dbus_bindings.DBusException: The name net.ekiga.instance was not
provided by any .service files


but
pacman -Ql ekiga | grep service
ekiga /opt/gnome/share/dbus-1/services/
ekiga /opt/gnome/share/dbus-1/services/net.ekiga.helper.service
ekiga /opt/gnome/share/dbus-1/services/net.ekiga.instance.service



dbus server is not configured to search for .service files in
/opt/gnome/share/dbus-1/ ; see /etc/dbus-1/session.conf for the service
directories ; here it looks only in /usr/share/dbus-1/services

and also talks about:

<!-- This configuration file controls the per-user-login-session message bus.
Add a session-local.conf and edit that rather than changing this
file directly. -->

those dbus guys!! they do not say where to put that local session so
it's parsed automatically!

but anyways we should not ask the user to actually hack session-loca.conf, but instead make sure that
/etc/dbus-1/session.conf

also looks in /opt/gnome/share/dbus-1/services/ and in /opt/kde/share/dbus-1/services [such a thing may exist in the future]

more: http://www.die.net/doc/linux/man/man1/dbus-daemon-1.1.html