Patexia seeks prior art for a patent that allegedly describes a method of accelerating an emergency call connection by a terminal device by skipping the special IMS (IP multimedia system) registration on a visiting network (such as a cellular mobile radio network, a WLAN, or WiMAX network) if the terminal device can determine that the visiting network matches its home network and that an IMS registration already exists.

During normal operation:

• the terminal detects a visiting network and send an IMS registration request
• the visiting network responds by providing its network identifier along with the IMS registration data necessary to set up a session initiation protocol (SIP) session for normal phone calls
• the terminal compares the received network identifier to a locally stored network identifier of its home network
• if a match, the terminal can conclude that it is registered, can make phone calls, and that it is on its home network

When an emergency call needs to be made:

• the terminal skips establishing an emergency call SIP URI (SIP uniform resource identifier, or emergency call public user identity)
• establishes the outbound emergency call using its existing SIP registration information made by the IMS during normal operation

Figure 1. Block Diagram of the Emergency Call Connection Shortcut

Questions

1. Was the reference filed or published before April 27th, 2006? (True/False)
2. Does the reference describe a terminal device that connects to a visiting network (either a cellular mobile radio network, a wireless local area network, or a WiMAX network), and receives from the visiting network a network identifier that includes a notification that the terminal is registered in its IMS?
3. Does the terminal compare the received network identifier to the network identifier of its own home network stored on the device to determine if (1) it is on its home network and (2) that an IMS registration already exists?
4. Does the terminal device skip the IMS registration process and make an emergency call connection via the previously confirmed IMS registration if both determinations (1 & 2) from question 3 are true?

Glossary

• IP multimedia subsystem (IMS) - an architectural framework for delivering IP multimedia services over a network and supported by fixed access, mobile access, and wireless access networks, where terminal devices must go through a registration process before being allowed to fully utilize the network
• Home network - a network transmitted from a base station that the terminal recognizes as being a subscriber to
• Visiting network - a network transmitted from a base station that might be a different base station that the terminal has not connected to before, but is still a base station belonging to the network provider that the terminal is a subscriber to