SylkServer

h1. Offline Message and audio mailbox Application

For this to work, both voice and chat offline messaging must be handled by SylkServer, Asterisk will be dropped.

 * Add failure route to OpenSIPS for chat sessions

 * SylkServer answers the session in behalf of the called user 

 * SylkServer sends an automatic answer with 'I am offline but you can type a message'

 * Session is automatically closed after 1 minute of inactivity and a MWI (RFC 3842) PUBLISH is on behalf of the caller to the proxy. The payload contains both Text-Messages, Voice-Messages (RFC 3458)

 * When the user comes back online she will subscribe to MWI and learn that she has offline text messages waiting. She can get them by starting a chat session to the URI in the Message-Account field of the MWI payload. Messages from multiple users are aggregated inside the same session using CPIM headers. Blink will save these messages in the local history and render separate tabs from each recipient.   

 * When the user fetches all messages SylkServer will terminate the session and send one last PUBLISH indicating that there are no new offline messages

 * SylkServer will provide a single URI for all users to fetch messages, the From header URI will be used to select the appropriate user. This assumes SylkServer is deployed behind a SIP proxy, which a by-design feature of SylkServer.

TODO: Visual voicemail functionality using MSRP pull