Hello, have a look at this recent discussion for an option/idea: https://lists.kamailio.org/pipermail/sr-users/2020-April/108930.html Cheers, Henning -- Henning Westerholt – https://skalatan.de/blog/ Kamailio services – https://gilawa.com<https://gilawa.com/> From: sr-users &lt;sr-users-bounces(a)lists.kamailio.org&gt; On Behalf Of Péter Barabás Sent: Friday, May 15, 2020 8:41 PM To: Kamailio (SER) - Users Mailing List &lt;sr-users(a)lists.kamailio.org&gt; Subject: [SR-Users] msilo dump, ordering Hi, I have a strange situation in messaging. I start to send messages continuously from one user to another on iOS devices. The messages are stored in silo since receiver is in background and registration does not exists. During the message flow, the receiver registers and the messages are dumped from silo when the sender still sends messages. The order of messages are important because of encryption, if an earlier message arrives after a later one to the receiver, a new key exchange is needed to decrypt messages, etc... So the question: - Is there any technique where I can delay or lock incoming messages on kamailio until silo messages successfully dumped in order to preserve message ordering? Thanks Peter