Patent ID: 9185140
Filing Date: 2015-11-10
Classification: H04L,H04W

Abstract:
1. A method comprising: a processor enabled SIP server establishing a Session Initiation Protocol (SIP) session dialog, between a first user agent and a second user agent; while the processor enabled SIP server is no longer aware of the SIP session dialog, the processor enabled SIP server receiving, from the first user agent, an in-dialog message for the SIP session dialog between the first user agent and the second user agent; in response to receiving the in-dialog message for the SIP session dialog between the first user agent and the second user agent, the processor enabled SIP server sending a request not found message to the first user agent, wherein the request not found message comprises a server accessible value; the processor enabled SIP server receiving, from the first user agent, an out-of-dialog SIP REFER message for the second user agent, wherein the out-of-dialog SIP REFER message comprises call state information for the SIP session dialog between the first user agent and the second user agent and wherein the out-of-dialog SIP REFER message is sent based on the server accessible value; sending, from the processor enabled SIP server, the out-of-dialog SIP REFER message to the second user agent; and reestablishing the SIP session dialog between the first user agent and the second user agent.