Abstract: Multiple timers used by a device during setup of a communication session may include a first timer and a second timer, each configured to expire after different periods of time, and each configured to start in response to the device sending a Session Initiation Protocol (SIP) request using a SIP INVITE method. The first timer is stopped on receipt of the first SIP response, which may include a 100 Trying SIP response, while the second timer is stopped on receipt of a non-100 Trying SIP response. If the first timer expires, the device may send an additional SIP request using the SIP INVITE method as a retry mechanism while the second timer continues to run. If the second timer expires, the device may halt the session setup and reattempt using a different type of access network.

Abstract: Multiple timers used by a device during setup of a communication session may include a first timer and a second timer, each configured to expire after different periods of time, and each configured to start in response to the device sending a Session Initiation Protocol (SIP) request using a SIP INVITE method. The first timer is stopped on receipt of the first SIP response, which may include a 100 Trying SIP response, while the second timer is stopped on receipt of a non-100 Trying SIP response. If the first timer expires, the device may send an additional SIP request using the SIP INVITE method as a retry mechanism while the second timer continues to run. If the second timer expires, the device may halt the session setup and reattempt using a different type of access network.

Abstract: A communication device may transmit messages to an Internet Protocol Multimedia Subsystem (IMS) network through an untrusted non-3GPP radio access network (RAN). A process to be implemented on a communication device may include generating a message having a location identifier (ID) that is indicative of a current location of the communication device, and transmitting the message, through an untrusted non-3GPP RAN, to a node within the IMS network. A process to be implemented on one or more nodes of the IMS network may include receiving, from a communication device and via an untrusted non-3GPP RAN, a message having a location ID, and in response to receiving the message, estimating a current location of the communication device based at least in part on the location ID.

Abstract: One or more timers can be used by an originating UE during setup of a communication session. The timer(s) can be triggered by an originating UE sending a request or receiving a response that uses a first signaling protocol. The timer(s) can further be terminated by the originating UE sending a request or receiving a response that uses a second signaling protocol different from the first signaling protocol, so long as the request/response using the second signaling protocol occurs before timeout of the timer(s).

Abstract: A system and method for performing an emergency call route failover between an Emergency Call Session Control Function (E-CSCF) and multi-homed remote end-point functions such as Border Gateway Control Function (BGCF)/Media Gateway Control Function (MGCF) or Interconnection Border Control Function (IBCF) in an Internet Protocol Multimedia Subsystem (IMS) uses Session Initiation Protocol (SIP) and/or Domain Name System (DNS) methods. The E-CSCF and/or a DNS server monitors the availability of the remote end-points to create a peer list of route options. The E-CSCF or the DNS server selects a route option from the peer list to route an emergency call to an appropriate Public Safety Answering Point (PSAP). In the event that the route option fails, the E-CSCF fails over to the next available route option to route the emergency call.

Abstract: One or more timers can be used by an originating UE during setup of a communication session. The timer(s) can be triggered by an originating UE sending a request or receiving a response that uses a first signaling protocol. The timer(s) can further be terminated by the originating UE sending a request or receiving a response that uses a second signaling protocol different from the first signaling protocol, so long as the request/response using the second signaling protocol occurs before timeout of the timer(s).

Abstract: A system and method for performing an emergency call route failover between an Emergency Call Session Control Function (E-CSCF) and multi-homed remote end-point functions such as Border Gateway Control Function(BGCF)/Media Gateway Control Function (MGCF) or Interconnection Border Control Function (IBCF) in an Internet Protocol Multimedia Subsystem (IMS) uses Session Initiation Protocol (SIP) and/or Domain Name System (DNS) methods. The E-CSCF and/or a DNS server monitors the availability of the remote end-points to create a peer list of route options. The E-CSCF or the DNS server selects a route option from the peer list to route an emergency call to an appropriate Public Safety Answering Point (PSAP). In the event that the route option fails, the E-CSCF fails over to the next available route option to route the emergency call.

Abstract: One or more timers can be used by an originating UE during setup of a communication session. The timer(s) can be triggered by an originating UE sending a request or receiving a response that uses a first signaling protocol. The timer(s) can further be terminated by the originating UE sending a request or receiving a response that uses a second signaling protocol different from the first signaling protocol, so long as the request/response using the second signaling protocol occurs before timeout of the timer(s).

Abstract: One or more timers can be used by an originating UE during setup of a communication session. The timer(s) can be triggered by an originating UE receiving a response from a node of a telecommunications network. The timer(s) can further be terminated by a particular termination event during a remainder of the session setup, so long as the termination event occurs before timeout of the timer(s).

Abstract: A system and method for performing an emergency call route failover between an Emergency Call Session Control Function (E-CSCF) and multi-homed remote end-point functions such as Border Gateway Control Function(BGCF)/Media Gateway Control Function (MGCF) or Interconnection Border Control Function (IBCF) in an Internet Protocol Multimedia Subsystem (IMS) uses Session Initiation Protocol (SIP) and/or Domain Name System (DNS) methods. The E-CSCF and/or a DNS server monitors the availability of the remote end-points to create a peer list of route options. The E-CSCF or the DNS server selects a route option from the peer list to route an emergency call to an appropriate Public Safety Answering Point (PSAP). In the event that the route option fails, the E-CSCF fails over to the next available route option to route the emergency call.

Abstract: A system and method for performing an emergency call route failover between an Emergency Call Session Control Function (E-CSCF) and multi-homed remote end-point functions such as Border Gateway Control Function(BGCF)/Media Gateway Control Function (MGCF) or Interconnection Border Control Function (IBCF) in an Internet Protocol Multimedia Subsystem (IMS) uses Session Initiation Protocol (SIP) and/or Domain Name System (DNS) methods. The E-CSCF and/or a DNS server monitors the availability of the remote end-points to create a peer list of route options. The E-CSCF or the DNS server selects a route option from the peer list to route an emergency call to an appropriate Public Safety Answering Point (PSAP). In the event that the route option fails, the E-CSCF fails over to the next available route option to route the emergency call.

Abstract: A communication device may transmit messages to an Internet Protocol Multimedia Subsystem (IMS) network through an untrusted non-3GPP radio access network (RAN). A process to be implemented on a communication device may include generating a message having a location identifier (ID) that is indicative of a current location of the communication device, and transmitting the message, through an untrusted non-3GPP RAN, to a node within the IMS network. A process to be implemented on one or more nodes of the IMS network may include receiving, from a communication device and via an untrusted non-3GPP RAN, a message having a location ID, and in response to receiving the message, estimating a current location of the communication device based at least in part on the location ID.

Abstract: A communication device may transmit messages to an Internet Protocol Multimedia Subsystem (IMS) network through an untrusted non-3GPP radio access network (RAN). A process to be implemented on a communication device may include generating a message having a location identifier (ID) that is indicative of a current location of the communication device, and transmitting the message, through an untrusted non-3GPP RAN, to a node within the IMS network. A process to be implemented on one or more nodes of the IMS network may include receiving, from a communication device and via an untrusted non-3GPP RAN, a message having a location ID, and in response to receiving the message, estimating a current location of the communication device based at least in part on the location ID.

Abstract: A method of selecting a location determination method for a mobile device within a wireless communication network. For example, the method may be selected based upon how the mobile device accessed the wireless communication network and the capabilities of the mobile device. Thus, possible technologies for determining the location of the mobile device include, but are not limited to, using a Location Retrieval Function (LRF), an Enhanced Serving Mobile Location Center (E-SMLC), a Global Positioning System (GPS), triangulation and accessing a National Emergency Address Database (NEAD). Additionally, multiple methods and/or technologies may be used to determine the mobile device's location and the method or methods may be selected based upon levels of trust with respect to the results.

Abstract: A system and method for performing an emergency call route failover between an Emergency Call Session Control Function (E-CSCF) and multi-homed remote end-point functions such as Border Gateway Control Function(BGCF)/Media Gateway Control Function (MGCF) or Interconnection Border Control Function (IBCF) in an Internet Protocol Multimedia Subsystem (IMS) uses Session Initiation Protocol (SIP) and/or Domain Name System (DNS) methods. The E-CSCF and/or a DNS server monitors the availability of the remote end-points to create a peer list of route options. The E-CSCF or the DNS server selects a route option from the peer list to route an emergency call to an appropriate Public Safety Answering Point (PSAP). In the event that the route option fails, the E-CSCF fails over to the next available route option to route the emergency call.

Abstract: A system and method for performing an emergency call route failover between an Emergency Call Session Control Function (E-CSCF) and multi-homed remote end-point functions such as Border Gateway Control Function (BGCF)/Media Gateway Control Function (MGCF) or Interconnection Border Control Function (IBCF) in an Internet Protocol Multimedia Subsystem (IMS) uses Session Initiation Protocol (SIP) and/or Domain Name System (DNS) methods. The E-CSCF and/or a DNS server monitors the availability of the remote end-points to create a peer list of route options. The E-CSCF or the DNS server selects a route option from the peer list to route an emergency call to an appropriate Public Safety Answering Point (PSAP). In the event that the route option fails, the E-CSCF fails over to the next available route option to route the emergency call.

Abstract: A communication device may transmit messages to an Internet Protocol Multimedia Subsystem (IMS) network through an untrusted non-3GPP radio access network (RAN). A process to be implemented on a communication device may include generating a message having a location identifier (ID) that is indicative of a current location of the communication device, and transmitting the message, through an untrusted non-3GPP RAN, to a node within the IMS network. A process to be implemented on one or more nodes of the IMS network may include receiving, from a communication device and via an untrusted non-3GPP RAN, a message having a location ID, and in response to receiving the message, estimating a current location of the communication device based at least in part on the location ID.

Abstract: A system and method to determine a type of wireless network that is to be used for an emergency communication session that is initiated at a mobile device. A Session Initiation Protocol (SIP) header is modified to introduce an emergency call mode preference (ECMP) field into the header. When a mobile device registers a session with an IP Multimedia Subsystem (IMS), the ECMP field is populated by the service provider with information that conveys the preferred network to use when an emergency communication session is initiated by a user of the mobile device. In the event of a subsequent request to start an emergency communication session using the mobile device, the mobile device utilizes the preferred network to establish communication.

Abstract: A system and method to determine a type of wireless network that is to be used for an emergency communication session that is initiated at a mobile device. A Session Initiation Protocol (SIP) header is modified to introduce an emergency call mode preference (ECMP) field into the header. When a mobile device registers a session with an IP Multimedia Subsystem (IMS), the ECMP field is populated by the service provider with information that conveys the preferred network to use when an emergency communication session is initiated by a user of the mobile device. In the event of a subsequent request to start an emergency communication session using the mobile device, the mobile device utilizes the preferred network to establish communication.