US Patent No. 9,107,196


Patent No. 9,107,196
Issue Date August 11, 2015
Title Reconnecting Dropped Calls Using An Internet Protocol Multimedia Subsystem
Inventorship Bejoy Pankajakshan, Olathe, KS (US)
Warren B. Cope, Olathe, KS (US)
Pallavur Sankaranaraynan, Overland Park, KS (US)
Assignee Sprint Communications Company L.P., Overland Park, KS (US)

Claim of US Patent No. 9,107,196

1. A method of operating a Session Initiation Protocol (SIP) system to control an Internet Protocol (IP) communication session
between a first communication device and a second communication device, the method comprising:
in a SIP control server, receiving a SIP bye message from the first communication device indicating a loss of the IP communication
session with the second communication device, and in response, transferring a notification request for the second communication
device to a SIP registration server, wherein the notification request requests a registration notification from the SIP registration
server when the second communication device re-registers with the SIP registration server;

in the SIP registration server, processing a SIP registration message from the second communication device, and in response
to the notification request and the SIP registration message, transferring the registration notification to the SIP control
server; and

in the SIP control server, receiving the registration notification for the second communication device, and in response to
the SIP bye message and the registration notification, transferring a SIP invite message to re-establish the IP communication
session to the first communication device.