To my knowledge, it’s not possible to use OpenSER
alone to do this.
Options include WeSIP (beta software, restrictive licence) or Asterisk
(poor implementation of “peer” identification limits usability). Could
anyone advise what other alternatives there are? Is it possible to just
use OpenSER? What about SEMS?
In the source tree, there is "examples/ctd.sh", which relies on the help
of the involved UACs (using REFER).
For just INVITE, SEMS is a good choice, and we plan to submit our
click2dial plugin into the trunk within the next days.
Andreas