# US 11,122,471 B2 · On-demand circuit-switched (CS) network registration

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- Number: US 11,122,471 B2
- Document ID: US11122471B2
- Status: Granted
- Kind: B2
- Application number: 16/593,439
- Filed: 2019-10-04
- Published: 2021-04-08
- Granted: 2021-09-14
- Earliest claimed: 2019-10-04
- Assignees: T-Mobile USA, Inc.
- Applicants: T-Mobile USA, Inc.
- Inventors: Hsin-Fu Henry Chiang; Suresh Thanneeru; Syed Toaha Ahmad; Boris Antsev
- Web page: https://patentgrep.com/patent/US11122471B2

## CPC

- H04W 48/18: Selecting a network or a communication service
- H04W 60/04: using triggered events
- H04W 4/14: Short messaging services, e.g. short message services [SMS] or unstructured supplementary service data [USSD]
- H04W 8/04: Registration at HLR or HSS [Home Subscriber Server]
- H04W 8/12: between location registers or mobility servers
- H04W 8/26: Network addressing or numbering for mobility support
- H04W 36/00224: {between packet switched [PS] and circuit switched [CS] network technologies, e.g. circuit switched fallback [CSFB]}
- H04W 60/005: {Multiple registrations, e.g. multihoming}
- H04W 76/16: Involving different core network technologies, e.g. a packet-switched [PS] bearer in combination with a circuit-switched [CS] bearer
- H04W 60/06: De-registration or detaching
- H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

Registration of a user equipment (UE) with a circuit-switched (CS) network can be controlled in an “on-demand” fashion by waiting for a trigger event before registering the UE with an available CS network. In some embodiments, CS registration of a UE may be triggered when the mobility management entity (MME) node receives, from the UE, a service request that was sent using Non-Access Stratum (NAS) protocol, such as an extended service request (ESR) or a short message service (SMS) over NAS request. In some embodiments, CS registration of a first UE may be triggered when the MME node receives, from a home subscriber server (HSS), a notification of an incoming session request originating from a second UE to establish a communication session over a CS network with the first UE.

## Claims

### Claim 1

A method comprising:
receiving, by a mobility management entity (MME) node of a telecommunications network, a combined attach request from a user equipment (UE);
sending, by the MME node, to the UE, a message indicating that the combined attach request is accepted;
determining, by the MME, that the UE is presently registered with a first circuit-switched (CS) network;
de-registering, by the MME and at least in part in response to receiving the combined attach request, the UE from the first CS network;
receiving, by the MME node, an extended service request (ESR) from the UE indicating that the UE is requesting to fall back to a second CS network; and
in response to receiving the combined attach request and the ESR from the UE:
registering the UE with the second CS network; and
establishing the voice-based communication session over the second CS network.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
terminating the voice-based communication session over the CS network; and
redirecting the UE from the second CS network to a packet-switched (PS) network based at least in part on terminating the voice-based compunction session.

### Claim 3 (depends on 1)

The method of claim 1, wherein:
receiving, by the MME node, a second combined attach request from the UE;
sending, by the MME node, to the UE, a second message indicating that the second combined attach request is accepted;
determining that the UE is presently registered with the second CS network; and
de-registering, by the MME node, the UE from the second CS network based on the UE being presently registered with the second CS network.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
in response to the receiving of the ESR from the UE, determining a number of UEs currently registered with the second CS network,
wherein the registering the UE with the second CS network is based at least in part on the number of UEs currently registered with the second CS network.

### Claim 5 (depends on 1)

The method of claim 1, wherein the ESR received from the UE was sent using Non-Access Stratum (NAS) protocol.

### Claim 6

A system comprising:
one or more processors; and
memory storing computer-executable instructions that, when executed by the one or more processors, cause the system to:
receive a combined attach request from a user equipment (UE);
determine that the UE is presently registered with a first circuit-switched (CS) network;
de-register, at least in part in response to receiving the combined attach request, the UE from the first CS network;
send, to the UE, a message indicating that the combined attach request is accepted;
receive a service request from the UE, the service request having been sent using Non-Access Stratum (NAS) protocol; and
in response to receiving the combined attach request and the service request from the UE, register the UE with a second circuit-switched (CS) network.

### Claim 7 (depends on 6)

The system of claim 6, wherein the one or more processors and the memory storing the computer-executable instructions are implemented on a mobility management entity (MME) node of a telecommunications network.

### Claim 8 (depends on 7)

The system of claim 7, wherein registering the UE with the CS network comprises sending, by the MME node, an identifier (ID) associated with the UE to a mobile switching station (MSS) of the second CS network.

### Claim 9 (depends on 6)

The system of claim 6, wherein the service request received from the UE comprises an extended service request (ESR), and wherein the computer-executable instructions, when executed by the one or more processors, further cause the system to establish a voice-based communication session over the second CS network in response to registering the UE with the second CS network.

### Claim 10 (depends on 9)

The system of claim 9, wherein the computer-executable instructions, when executed by the one or more processors, further cause the system to:
terminate the voice-based communication session over the second CS network; and
redirect the UE to a packet-switched (PS) network based at least in part on terminating the voice-based communication session.

### Claim 11 (depends on 6)

The system of claim 6, wherein the service request received from the UE comprises a Short Message Service (SMS) over NAS request.

### Claim 12 (depends on 6)

The system of claim 6, wherein the computer-executable instructions, when executed by the one or more processors, further cause the system to:
receive a second combined attach request from the UE;
send, to the UE, a second message indicating that the second combined attach request is accepted; and
de-register the UE from the second CS network.

### Claim 13 (depends on 6)

The system of claim 6, wherein the computer-executable instructions, when executed by the one or more processors, further cause the system to:
in response to receiving the service request from the UE, determine a number of UEs currently registered with the second CS network,
wherein registering the UE with the second CS network is based at least in part on the number of UEs currently registered with the second CS network.

### Claim 14

A method comprising:
receiving, by a mobility management entity (MME) node of a telecommunications network, a combined attach request from a first user equipment (UE);
sending, by the MME node, to the first UE, a message indicating that the combined attach request is accepted;
refraining, at least in part in response to receiving the combined attach request, from registering the UE with a circuit-switched (CS) network;
receiving, by the MME node, from a Home Subscriber Server (HSS), a notification of an incoming session request originating from a second UE to establish a communication session over the CS network with the first UE; and
in response to receiving the attach request and the notification from the HSS, registering, by the MME node, the first UE with the CS network.

### Claim 15 (depends on 14)

The method of claim 14, wherein the communication session is a voice-based communication session, the method further comprising sending, by the MME node, a page request to the first UE for establishing the voice-based communication session over the CS network.

### Claim 16 (depends on 15)

The method of claim 15, further comprising:
terminating the voice-based communication session over the CS network; and
redirecting the first UE to a packet-switched (PS) network based at least in part on terminating the voice-based communication session.

### Claim 17 (depends on 14)

The method of claim 14, further comprising:
receiving, by the MME node, a second combined attach request from the first UE;
sending, by the MME node, to the first UE, a second message indicating that the second combined attach request is accepted; and
de-registering, by the MME node, the UE from the CS network.

### Claim 18 (depends on 14)

The method of claim 14, further comprising:
in response to the receiving of the notification from the HSS, determining a number of UEs currently registered with the CS network,
wherein the registering the first UE with the CS network is based at least in part on the number of UEs currently registered with the CS network.

### Claim 19 (depends on 14)

The method of claim 14, wherein the registering the first UE with the CS network comprises sending, by the MME node, an identifier (ID) associated with the first UE to a mobile switching station (MSS).

### Claim 20 (depends on 19)

The method of claim 19, further comprising, after the sending the ID associated with the first UE to the MSS:
sending, by the MSS, a location update to a Home Location Register (HLR);
receiving, by the MSS, from a second MSS, information associated with the incoming session request; and
sending, by the MSS, to the MME node, the information, or different information based on the information, to include in a page request to the first UE for establishing the communication session over the CS network.