msilo module provides offline SIP MESSAGE storage for the OpenSER. It stores received messages from an offline user and send them when the user becomes online. The service is similar to the ones offered by well-known IM networks: Jabber/XMPP, Yahoo!, AIM, Skype, …
If the SIP phone is able to advertise supported SIP methods, the module doesn’t try to send MESSAGE requests to phones not supporting them. It can be used to send reminders as well, a stored message can be armed to be delivered at a specific time.