The issue is in the tm module. While processing the resumed reply, since we are in a case of final reply for the transaction, we delete it after sending it out. This is causing the carsh when, at the end of t_continue we try to access the branch's reply. I've open a PR https://github.com/kamailio/kamailio/pull/1063 with a fix. Also, why do you need to suspend the reply in this case? Wouldn't be fine to not suspend the transaction? See $http_req(suspend) http://www.kamailio.org/docs/modules/devel/modules/http_async_client.html#id....