# US 11,444,858 B2 · Disconnection monitoring terminating device and disconnection monitoring method

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- Number: US 11,444,858 B2
- Document ID: US11444858B2
- Status: Granted
- Kind: B2
- Application number: 16/979,979
- Filed: 2019-03-07
- Published: 2021-11-25
- Granted: 2022-09-13
- Earliest claimed: 2018-03-12
- Assignees: Nippon Telegraph and Telephone Corporation
- Applicants: Nippon Telegraph and Telephone Corporation
- Inventors: Muneaki Ogawa; Kenjiro Arai
- Web page: https://patentgrep.com/patent/US11444858B2

## CPC

- H04L 67/145: avoiding end of session, e.g. keep-alive, heartbeats, resumption message or wake-up for inactive or interrupted session
- H04L 43/0811: by checking connectivity
- H04L 65/1069: Session establishment or de-establishment
- H04L 65/1104: Session initiation protocol [SIP]
- H04L 65/65: Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
- H04L 69/22: Parsing or analysis of headers
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

It is possible to appropriately avoid erroneous call disconnection between interconnected networks at a low cost without modifying an apparatus in the network. A disconnection monitoring termination apparatus 1 is connected between a first network 100 for monitoring for inability to communicate RTP packets in a second network 200 by using a disconnection monitoring timer and the second network for accommodating terminals that do not send a hold signal, monitors for the inability to communicate the RTP packets in the second network 200 by using the disconnection monitoring timer for second network monitoring having a value smaller than a value of the disconnection monitoring timer of the first network 100, and when detecting the inability to communicate the RTP packets in the second network 200, the disconnection monitoring termination apparatus 1 sends an UPDATE request or a re-INVITE request including an SDP offer in which a direction attribute of “a=recvonly” is set, to the first network 100.

## Claims

### Claim 1

A disconnection monitoring termination apparatus operable to be connected between a first network configured to monitor for inability to communicate real time transport protocol (RTP) packets in a second network by using a disconnection monitoring timer and the second network configured to accommodate terminals that do not send a hold signal, the disconnection monitoring termination apparatus comprising:
a signal control unit, implemented using one or more computing devices, configured to control a signal transmitted and received between the first network and the second network;
a disconnection monitoring timer storage unit, implemented using one or more computing devices, configured to store a value of a disconnection monitoring timer for second network monitoring used for monitoring for the inability to communicate the RTP packets in the second network;
a disconnection monitoring timer setting unit, implemented using one or more computing devices, configured to set the value of the disconnection monitoring timer for second network monitoring to a value smaller than a value of the disconnection monitoring timer of the first network; and
an RTP disconnection monitoring unit, implemented using one or more computing devices, configured to monitor for the inability to communicate the RTP packets in the second network, by using the disconnection monitoring timer for second network monitoring,
wherein the signal control unit is configured to, based on the RTP disconnection monitoring unit detecting the inability to communicate the RTP packets in the second network, send a request including a session description protocol (SDP) offer in which a direction attribute of receive only is set, to the first network.

### Claim 2

A disconnection monitoring method executed by a disconnection monitoring termination apparatus, the disconnection monitoring termination apparatus operable to be connected between a first network configured to monitor for inability to communicate real time transport protocol (RTP) packets in a second network by using a disconnection monitoring timer and the second network configured to accommodate terminals that do not send a hold signal, the disconnection monitoring method comprising:
storing a value of a disconnection monitoring timer for second network monitoring used for monitoring for the inability to communicate the RTP packets in the second network, in a disconnection monitoring timer storage unit;
setting the value of the disconnection monitoring timer for second network monitoring to a value smaller than a value of the disconnection monitoring timer of the first network;
controlling a signal transmitted and received between the first network and the second network; and
monitoring, by an RTP disconnection monitoring unit implemented in the disconnection monitoring termination apparatus, for the inability to communicate the RTP packets in the second network, by using the disconnection monitoring timer for second network monitoring,
wherein, while controlling the signal, based on the RTP disconnection monitoring unit detecting inability to communicate the RTP packets in the second network, a request including a session description protocol (SDP) offer in which a direction attribute of receive only set is sent to the first network.

### Claim 3

A disconnection monitoring method executed by a disconnection monitoring termination apparatus, the disconnection monitoring termination apparatus operable to be connected between a first network and a second network that are respectively configured to monitor for inability to communicate real time transport protocol (RTP) packets in the second network or the first network by respectively using disconnection monitoring timers having different values, the disconnection monitoring method comprising:
storing a value of a disconnection monitoring timer held by the first network and a value of a disconnection monitoring timer held by the second network, in a network disconnection monitoring timer storage unit;
storing a value of a disconnection monitoring timer for monitoring both networks used for monitoring for inability to communicate RTP packets in both networks of the first network and the second network, in a disconnection monitoring timer storage unit;
setting the value of the disconnection monitoring timer for monitoring both networks to a value smaller than the value of the disconnection monitoring timer held by the first network and the value of the disconnection monitoring timer held by the second network;
controlling a signal transmitted and received between the first network and the second network; and
monitoring for the inability to communicate the RTP packets in each of the first network and the second network, by using the disconnection monitoring timer for monitoring both networks,
wherein, while controlling the signal, based on the disconnection monitoring termination apparatus detecting the inability to communicate RTP packets in one network having a larger value of the disconnection monitoring timer among the first network and the second network, a request in which a direction attribute of receive only is set is sent to the other network.

### Claim 4 (depends on 1)

The disconnection monitoring termination apparatus of claim 1, wherein the signal is a session initiation protocol (SIP) signal or an RTP packet.

### Claim 5 (depends on 1)

The disconnection monitoring termination apparatus of claim 1, wherein the signal control unit is configured to, based on an RTP packet being received, send an update request or a re-invite request including an SDP offer in which a direction attribute of send and receive is set, to the first network.

### Claim 6 (depends on 2)

The disconnection monitoring method of claim 2, wherein the signal is a session initiation protocol (SIP) signal or an RTP packet.

### Claim 7 (depends on 2)

The disconnection monitoring method of claim 2, further comprising, based on an RTP packet being received, sending an update request or a re-invite request including an SDP offer in which a direction attribute of send and receive is set, to the first network.

### Claim 8 (depends on 3)

The disconnection monitoring method of claim 3, wherein the signal is a session initiation protocol (SIP) signal or an RTP packet.

### Claim 9 (depends on 3)

The disconnection monitoring method of claim 3, further comprising, based on an RTP packet being received, sending an update request or a re-invite request including an SDP offer in which a direction attribute of send and receive is set, to the first network.