Patent Description:
As communication technology advances, two or more communication networks can be used together. For example, previously, third generation (<NUM>) communication and long term evolution (LTE) communication have been used at the same time, and now LTE communication and fifth generation (<NUM>) communication can be used together. <NUM> communication, which is under development, cannot support all services supported by LTE communication. Consequently, when an electronic device connected to <NUM> communication intends to use a service that is not supported by <NUM> communication, the electronic device may need to switch the communication network to LTE communication.

If a service cannot be provided to the user through a communication network to which an electronic device is connected, the electronic device may connect to a second communication network. While being connected to the second communication network, the electronic device may be unable to transmit a message to a second electronic device. The electronic device may also be unable to receive a message transmitted by the second electronic device. In some cases, the second electronic device cannot confirm whether the electronic device has received the transmitted message.

After the electronic device is connected to the second communication network, it may be necessary to newly transmit and receive some messages according to the transmission protocol, and thus there may be a time delay in providing a service to the user.

<CIT>) discloses methods, systems, and apparatuses for asserting support for telematics capabilities in a vehicle emergency call system.

<CIT>) discloses apparatuses, methods, and systems for selecting a transport layer protocol for SIP messages.

Embodiments of the disclosure provide a method for shortening the call connection time and an electronic device thereof.

Embodiments of the disclosure provide an electronic device and method that can shorten the call connection time when it is necessary to switch the communication network because the currently connected communication network does not support a call connection.

Embodiments of the disclosure provide an electronic device that can shorten the call connection time even when the counterpart electronic device switches the communication network.

According to various example embodiments of the disclosure, an electronic device connected to a first communication network is provided according to claim <NUM>. The electronic device includes:
a communication module comprising communication circuitry; a processor operatively connected to the communication module; and a memory operatively connected to the processor, wherein the memory stores instructions that, when executed, cause the processor to control the electronic device to: transmit a message requesting a call connection through a first transmission protocol to an external electronic device using the communication module connected to the first communication network; receive a provisional response message for the request through the first transmission protocol from the external electronic device using the communication module connected to the first communication network; the memory further stores instructions that, when executed, cause the processor to control the electronic device to: after receiving the provisional response message, switch connection of the communication module from the first communication network to a second communication network based on the call connection not being supported by the first communication network;transmit a response message for the received provisional response message through a second transmission protocol to the external electronic device using the communication module connected to the second communication network, wherein the response message further includes information indicating that the electronic device has completed communication network switching; and perform the call connection using the communication module connected to the second communication network.

According to various example embodiments of the disclosure, an electronic device connected to a first communication network is provided according to claim <NUM>. The electronic device includes:.

According to various example embodiments of the disclosure, an operation method of an electronic device connected to a first communication network is provided according to claim <NUM>. The operation method includes:.

According to various example embodiments of the disclosure, an operation method of an electronic device connected to a first communication network is provided. The operation method may include: receiving a message requesting a call connection from an external electronic device using a first transmission protocol; transmitting a provisional response message for the request to the external electronic device using the first transmission protocol; connecting to a second communication network based on the call connection not being supported by the first communication network; retransmitting the provisional response message to the external electronic device using a second transmission protocol; and performing the call connection using the connected second communication network.

According to various example embodiments of the disclosure, when it is necessary to switch the communication network because the currently connected communication network does not support a call connection, the electronic device can shorten the call connection time.

According to various example embodiments of the disclosure, the electronic device can shorten the call connection time even when the counterpart electronic device switches the communication network.

Hereinafter, various example embodiments of the disclosure will be described in greater detail with reference to accompanying drawings.

<FIG> is a block diagram illustrating an example electronic device <NUM> in a network environment <NUM> according to various embodiments.

According to an embodiment, the antenna module <NUM> may include an antenna including a radiating element including a conductive material or a conductive pattern formed in or on a substrate (e.g., PCB).

<FIG> is a block diagram <NUM> illustrating an example electronic device <NUM> for supporting legacy network communication and <NUM> network communication according to various embodiments. Referring to <FIG>, the electronic device <NUM> may include a first communication processor <NUM>, a second communication processor <NUM>, a first radio frequency integrated circuit (RFIC) <NUM>, a second RFIC <NUM>, a third RFIC <NUM>, a fourth RFIC <NUM>, a first radio frequency front end (RFFE) <NUM>, a second RFFE <NUM>, a first antenna module <NUM>, a second antenna module <NUM>, and an antenna <NUM>. The electronic device <NUM> may further include the processor <NUM> and the memory <NUM>. The network <NUM> may include a first network <NUM> and a second network <NUM>. According to another embodiment, the electronic device <NUM> may further include at least one component among the components illustrated in <FIG>, and the network <NUM> may further include at least one other network. According to an embodiment, the first communication processor <NUM>, the second communication processor <NUM>, the first RFIC <NUM>, the second RFIC <NUM>, the fourth RFIC <NUM>, the first RFFE <NUM>, and the second RFFE <NUM> may be included as at least a part of the wireless communication module <NUM>. According to another embodiment, the fourth RFIC <NUM> may be omitted or may be included as a part of the third RFIC <NUM>.

The first communication processor <NUM> may establish a communication channel of a band to be used for wireless communication with the first network <NUM>, and may support legacy network communication via the established communication channel. According to certain embodiments, the first network may be a legacy network including <NUM>, <NUM>, <NUM>, or long term evolution (LTE) network. The second communication processor <NUM> may establish a communication channel corresponding to a designated band (e.g., approximately <NUM> to <NUM>) among bands to be used for wireless communication with the second network <NUM>, and may support <NUM> network communication via the established channel. According to certain embodiments, the second network <NUM> may be a <NUM> network defined in 3GPP. Additionally, according to an embodiment, the first communication processor <NUM> or the second communication processor <NUM> may establish a communication channel corresponding to another designated band (e.g., lower than <NUM>) among bands to be used for wireless communication with the second network <NUM>, and may support <NUM> network communication via the established channel. According to an embodiment, the first communication processor <NUM> and the second communication processor <NUM> may be implemented in a single chip or a single package. According to certain embodiments, the first communication processor <NUM> or the second communication processor <NUM> may be implemented in a single chip or a single package, together with the processor <NUM>, the sub-processor <NUM>, or the communication module <NUM>.

In the case of transmission, the first RFIC <NUM> may convert a baseband signal generated by the first communication processor <NUM> into a radio frequency (RF) signal in a range of approximately <NUM> to <NUM> used for the first network <NUM> (e.g., a legacy network). In the case of reception, an RF signal is obtained from the first network <NUM> (e.g., a legacy network) via an antenna (e.g., the first antenna module <NUM>), and may be preprocessed via an RFFE (e.g., the first RFFE <NUM>). The first RFIC <NUM> may convert the preprocessed RF signal to a baseband signal so that the base band signal is processed by the first communication processor <NUM>.

In the case of transmission, the second RFIC <NUM> may convert a baseband signal generated by the first communication processor <NUM> or the second communication processor <NUM> into an RF signal (hereinafter, a <NUM> Sub6 RF signal) of a Sub6 band (e.g., lower than <NUM>) used for the second network <NUM> (e.g., <NUM> network). In the case of reception, a <NUM> Sub6 RF signal is obtained from the second network <NUM> (e.g., a <NUM> network) via an antenna (e.g., the second antenna module <NUM>), and may preprocessed by an RFFE (e.g., the second RFFE <NUM>). The second RFIC <NUM> may convert the preprocessed <NUM> Sub6 RF signal into a baseband signal so that the baseband signal is processed by a corresponding communication processor from among the first communication processor <NUM> or the second communication processor <NUM>.

The third RFIC <NUM> may convert a baseband signal generated by the second communication processor <NUM> into an RF signal (hereinafter, a <NUM> Above6 RF signal) of a <NUM> Above6 band (e.g., approximately <NUM> to <NUM>) to be used for the second network <NUM> (e.g., <NUM> network). In the case of reception, a <NUM> Above6 RF signal is obtained from the second network <NUM> (e.g., a <NUM> network) via an antenna (e.g., the antenna <NUM>), and may be preprocessed by the third RFFE <NUM>. The third RFIC <NUM> may convert the preprocessed <NUM> Above6 RF signal to a baseband signal so that the base band signal is processed by the second communication processor <NUM>. According to an embodiment, the third RFFE <NUM> may be implemented as a part of the third RFIC <NUM>.

According to an embodiment, the electronic device <NUM> may include the fourth RFIC <NUM>, separately from or as a part of the third RFIC <NUM>. In this instance, the fourth RFIC <NUM> may convert a baseband signal generated by the second communication processor <NUM> into an RF signal (hereinafter, an IF signal) in an intermediate frequency band (e.g., approximately <NUM> to <NUM>), and may transfer the IF signal to the third RFIC <NUM>. The third RFIC <NUM> may convert the IF signal to a <NUM> Above6 RF signal. In the case of reception, a <NUM> Above6 RF signal is received from the second network <NUM> (e.g., a <NUM> network) via an antenna (e.g., the antenna <NUM>), and may be converted into an IF signal by the third RFFE <NUM>. The fourth RFIC <NUM> may convert the IF signal to a baseband signal so that the base band signal is processed by the second communication processor <NUM>.

According to an embodiment, the first RFIC <NUM> and the second RFIC <NUM> may be implemented as a single chip or at least a part of the single package. According to an embodiment, the first RFFE <NUM> and the second RFFE <NUM> may be implemented as a single chip or at least a part of the single package. According to an embodiment, at least one antenna module of the first antenna module <NUM> or the second antenna module <NUM> may be omitted, or may be combined with another antenna module so as to process RF signals in a plurality of bands.

According to an embodiment, the third RFIC <NUM> and the antenna <NUM> may be disposed in the same substrate, and may form the third antenna module <NUM>. For example, the wireless communication module <NUM> or the processor <NUM> may be disposed in a first substrate (e.g., main PCB). In this instance, the third RFIC <NUM> is disposed in a part (e.g., a lower part) of the second substrate (e.g., a sub PCB) separate from the first substrate and the antenna <NUM> is disposed on another part (e.g., an upper part), so that the third antenna module <NUM> is formed. By disposing the third RFIC <NUM> and the antenna <NUM> in the same substrate, the length of a transmission line therebetween may be reduced. For example, this may reduce a loss (e.g., attenuation) of a signal in a high-frequency band (e.g., approximate <NUM> to <NUM>) used for <NUM> network communication, the loss being caused by a transmission line. Accordingly, the electronic device <NUM> may improve the quality or speed of communication with the second network <NUM> (e.g., <NUM> network).

According to an embodiment, the antenna <NUM> may be implemented as an antenna array including a plurality of antenna elements which may be used for beamforming. In this instance, the third RFIC <NUM> may be, for example, a part of the third RFFE <NUM>, and may include a plurality of phase shifters <NUM> corresponding to a plurality of antenna elements. In the case of transmission, each of the plurality of phase shifters <NUM> may shift the phase of a <NUM> Above6RF signal to be transmitted to the outside of the electronic device <NUM> (e.g., a base station of a <NUM> network) via a corresponding antenna element. In the case of reception, each of the plurality of phase shifters <NUM> may shift the phase of the <NUM> Above6 RF signal received from the outside via a corresponding antenna element into the same or substantially the same phase. This may enable transmission or reception via beamforming between the electronic device <NUM> and the outside.

The second network <NUM> (e.g., <NUM> network) may operate independently (e.g., Stand-Along (SA)) from the first network <NUM> (e.g., a legacy network), or may operate by being connected thereto (e.g., Non-Stand Alone (NSA)). For example, in the <NUM> network, only an access network (e.g., <NUM> radio access network (RAN) or next generation RAN (NG RAN)) may exist, and a core network (e.g., next generation core (NGC)) may not exist. In this instance, the electronic device <NUM> may access an access network of the <NUM> network, and may access an external network (e.g., the Internet) under the control of the core network (e.g., an evolved packed core (EPC)) of the legacy network. Protocol information (e.g., LTE protocol information) for communication with the legacy network or protocol information (e.g., New Radio (NR) protocol information) for communication with the <NUM> network may be stored in the memory <NUM>, and may be accessed by another component (e.g., the processor <NUM>, the first communication processor <NUM>, or the second communication processor <NUM>).

<FIG> is a signal flow diagram illustrating an example of call processing between electronic devices according to various embodiments.

For example, the first electronic device <NUM> (e.g., electronic device <NUM> in <FIG>) may attempt to connect a call to the second electronic device <NUM> (e.g., electronic device <NUM> in <FIG>).

For control processing of a call or a session, an electronic device may transmit a session initiation protocol (SIP) message. SIP messages may include a request message and a response message, and may be transmitted using, for example, the user datagram protocol (UDP) or the transmission control protocol (TCP). For example, when the maximum segment unit (MSS) denotes the size of pure data excluding the header in one packet, if a SIP message has a size greater than the MSS, the transmission control protocol may be used to transmit the SIP message; and if the SIP message has a size less than the MSS, the user datagram protocol can be used to transmit the SIP message.

The transmission control protocol may include, for example, a protocol that provides reliable data transmission, flow control, and congestion control between the transmitting electronic device and the receiving electronic device. The user datagram protocol may include, for example, a protocol that allows the transmitting electronic device to unilaterally transmit data and is configured so that the transmitting electronic device cannot and does not need to check whether the receiving electronic device has received the data.

At operation <NUM>, the first electronic device <NUM> may transmit an Invite as a SIP request message for call connection.

At operation <NUM>, as a provisional response in reply to the Invite, the second electronic device <NUM> may transmit a <NUM> Session Progress as a SIP response message. The <NUM> Session Progress may include information being processed.

The second electronic device <NUM> may perform a call connection using the currently connected communication network, but if the currently connected communication network cannot support a call connection, the second electronic device <NUM> may perform a call connection using another communication network.

Hereinafter, examples in which the communication network currently connected to the second electronic device <NUM> supports a call connection and does not support a call connection may be described separately.

When the communication network to which the second electronic device <NUM> is currently connected supports a call connection (<NUM>), at operation <NUM>, the first electronic device <NUM> may transmit a provisional response acknowledgment (PRACK) as a SIP request message in reply to the <NUM> Session Progress. The first electronic device <NUM> may provide a reliable provisional response for a session that has not yet been established by transmitting a PRACK. As the second electronic device <NUM> performs a call connection using the currently connected communication network, the second electronic device <NUM> may receive the PRACK transmitted by the first electronic device <NUM>.

The second electronic device <NUM> may connect to another communication network when the currently connected communication network cannot support a call connection (<NUM>).

At operation <NUM>, the second electronic device <NUM> may perform, for example, evolved packet system (EPS) fallback. While evolved packet system (EPS) fallback is in progress, the second electronic device <NUM> may be unable to receive a message transmitted by another electronic device (e.g., first electronic device <NUM>), so messages transmitted by other electronic devices may be lost. Also, while evolved packet system (EPS) fallback is in progress, the second electronic device <NUM> may be unable to transmit a message to the other electronic device <NUM>.

At operation <NUM>, the first electronic device <NUM> may transmit a PRACK as a SIP request message. As the size of the PRACK may be less than the MSS, and the first electronic device <NUM> may transmit the PRACK thorough the user datagram protocol (UDP). If no response is received from the second electronic device <NUM> after transmitting the PRACK, the first electronic device <NUM> may retransmit the PRACK according to the message transmission protocol standard. For example, the retransmission time interval may be determined according to a timer value, and the timer value of the user datagram protocol may be <NUM> seconds.

At operation <NUM>, the first electronic device <NUM> may retransmit the PRACK according to the message transmission protocol standard. However, if evolved packet system fallback is in progress, the second electronic device <NUM> may be unable to receive the PRACK and may be unable to transmit any response. Similarly, if no response is still received from the second electronic device <NUM> after transmitting the PRACK, the first electronic device <NUM> may retransmit the PRACK according to the message transmission protocol standard. For example, the second retransmission time interval may also be determined according to the timer value, and the second retransmission time interval for the user datagram protocol may be <NUM> seconds as twice the timer value.

At operation <NUM>, the first electronic device <NUM> may retransmit the PRACK according to the message transmission protocol standard until a response is received from the second electronic device <NUM>. After completion of evolved packet system fallback, the second electronic device <NUM> may receive the PRACK. However, if the user no longer wants to connect a call, the first electronic device <NUM> may not transmit the PRACK.

At operation <NUM>, upon receiving the PRACK, the second electronic device <NUM> may transmit a <NUM> OK as a SIP response message regardless of the connected communication network.

Although the second electronic device <NUM> is able to receive a PRACK after evolved packet system (EPS) fallback is completed, as the first electronic device <NUM> does not transmit a PRACK, the second electronic device <NUM> may not receive the PRACK. As the second electronic device <NUM> needs to receive a PRACK transmitted by the first electronic device <NUM> to perform the next operation, the delay time for a call connection may be increased correspondingly. The delay time of a call connection may vary depending on whether a specific interface is supported in the connected communication network and the execution time of evolved packet system fallback. For example, when the connected communication network supports the N26 interface between the mobility management entity (MME) of the evolved packet system and the access and mobility management function (AMF) of the <NUM> system, as the execution time of evolved packet system fallback is shortened, the delay time of a call connection can also be shortened. The N26 interface may be selectively supported by the network operator.

Although <FIG> illustrates an example in which evolved packet system fallback occurs in the electronic device receiving a call connection request, evolved packet system fallback may also be performed in the electronic device requesting a call connection.

According to various embodiments of the disclosure, a method that can shorten the delay of a call connection even when evolved packet system fallback is performed is described for each electronic device performing evolved packet system fallback.

Although a call connection will be described as an example in the following description, various embodiments of the disclosure may be applicable to any service provided by an electronic device using a communication network.

<FIG> is a signal flow diagram illustrating an example of call processing when evolved packet system (EPS) fallback is performed in the receiving electronic device according to various embodiments.

According to various embodiments of the disclosure, as the communication network to which the receiving electronic device <NUM> (e.g., second electronic device <NUM> in <FIG>) is currently connected does not support the call connection requested by the transmitting electronic device <NUM> (e.g., first electronic device <NUM> in <FIG>), the receiving electronic device <NUM> may perform evolved packet system (EPS) fallback.

At operation <NUM>, the transmitting electronic device <NUM> may transmit an Invite as a SIP request message for call connection.

At operation <NUM>, as a provisional response in reply to the Invite, the second electronic device <NUM> may transmit a <NUM> Session Progress as a SIP response message.

At operation <NUM>, when the currently connected communication network cannot support the call connection, the receiving electronic device <NUM> may perform evolved packet system (EPS) fallback for connecting to a different communication network.

At operation <NUM>, the transmitting electronic device <NUM> may transmit a PRACK as a SIP request message in reply to the <NUM> Session Progress.

At operation <NUM>, if no response is received for the PRACK, the transmitting electronic device <NUM> may retransmit the PRACK.

While performing evolved packet system fallback, the receiving electronic device <NUM> may fail to receive the PRACK transmitted by the transmitting electronic device <NUM>, and the PRACK not received may be lost.

At operation <NUM>, when evolved packet system fallback is completed, the receiving electronic device <NUM> may retransmit the <NUM> Session Progress using a SIP response message without waiting for a PRACK from the transmitting electronic device <NUM>. The SIP response message can be transmitted using the transmission control protocol (TCP) regardless of its size. The SIP response message may further include information indicating completion of evolved packet system fallback. For example, information indicating completion of evolved packet system fallback may be included in the header of the SIP response message. Alternatively, the receiving electronic device <NUM> may separately notify that EPS fallback is completed.

At operation <NUM>, upon detecting information indicating completion of evolved packet system fallback, the transmitting electronic device <NUM> may immediately retransmit the PRACK.

At operation <NUM>, the receiving electronic device <NUM> may transmit a <NUM> OK using a SIP response message in reply to the PRACK.

<FIG> is a signal flow diagram illustrating an example of call processing when evolved packet system (EPS) fallback is performed in the transmitting electronic device according to various embodiments.

According to various embodiments of the disclosure, the transmitting electronic device <NUM> (e.g., transmitting electronic device <NUM> in <FIG>) attempts to connect a call according to the user's request, but when the currently connected communication network does not support a call connection, it may perform evolved packet system (EPS) fallback.

Operations <NUM> and <NUM> are the same as or similar to operations <NUM> and <NUM> in <FIG>, and descriptions thereof may not be repeated here.

At operation <NUM>, when the currently connected communication network cannot support a call connection, the transmitting electronic device <NUM> may perform evolved packet system fallback for connecting to another communication network. For example, the transmitting electronic device <NUM> may be connected to a fifth generation (<NUM>) network. The <NUM> network to which the transmitting electronic device <NUM> is connected may not support VoNR (voice/video over new radio), or may be unable to support VoNR due to another reason, for example, an increase in call volume. In this case, when the user requests a call connection for a video call, as the currently connected <NUM> network cannot support the video call, the transmitting electronic device <NUM> may perform evolved packet system fallback to a long term evolution (LTE) network.

At operation <NUM>, the transmitting electronic device <NUM> may attempt to transmit a PRACK separately from performing evolved packet system fallback. However, during execution of evolved packet system fallback, the PRACK may be stored only in the memory of the transmitting electronic device <NUM> without being transmitted to the outside.

At operation <NUM>, when the execution of evolved packet system fallback is completed, the transmitting electronic device <NUM> may immediately transmit a PRACK using a SIP request message. As the size of a PRACK may be less than the MSS, the user datagram protocol is generally used, but the transmission control protocol (TCP) may be used regardless of the PRACK size according to various embodiments of the disclosure.

At operation <NUM>, the receiving electronic device <NUM> (e.g., receiving electronic device <NUM> in <FIG>) may transmit a <NUM> OK using a SIP response message in reply to the PRACK.

<FIG> is a signal flow diagram illustrating an example of call processing when evolved packet system (EPS) fallback is performed in both the transmitting electronic device and the receiving electronic device according to various embodiments.

According to various embodiments of the disclosure, evolved packet system fallback can be performed not only in the transmitting electronic device <NUM> (e.g., transmitting electronic device <NUM> in <FIG>) but also in the receiving electronic device <NUM> (e.g., receiving electronic device <NUM> in <FIG>).

Operation <NUM> and operation <NUM> are the same as or similar to operation <NUM> and operation <NUM> in <FIG> and operation <NUM> and operation <NUM> in <FIG>, and descriptions thereof may not be repeated here.

At operation <NUM>, when the currently connected communication network cannot support a call connection, the transmitting electronic device <NUM> may perform evolved packet system fallback for connecting to another communication network. For example, in a situation where the transmitting electronic device <NUM> is connected to a <NUM> (generation) network that does not support VoNR, when the user requests a call connection for a video call, the transmitting electronic device <NUM> may perform evolved packet system fallback.

At operation <NUM>, when the currently connected communication network cannot support a call connection, the receiving electronic device <NUM> may also perform evolved packet system fallback for connecting to another communication network.

Although both the transmitting electronic device <NUM> and the receiving electronic device <NUM> perform evolved packet system fallback, the times required for the devices to perform evolved packet system fallback may be different. For example, when the network operator to which each electronic device belongs supports the N26 interface, the time required to perform evolved packet system fallback may be shorter compared with a case where the N26 interface is not supported. The N26 interface may, for example, be an interface that connects the mobility management entity (MME) of the LTE communication network and the access and mobility management function (AMF) of the <NUM> communication network. As another example, depending on the surrounding environment of each electronic device, for example, when there are many electronic devices connected to one base station or when the electronic device is far away from the base station, the time required to perform evolved packet system fallback may be increased.

At operation <NUM>, the transmitting electronic device <NUM> may transmit a PRACK when evolved packet system fallback is completed. In various embodiments of the disclosure, the transmission control protocol may be used regardless of the PRACK size. While performing evolved packet system fallback, the receiving electronic device <NUM> may fail to receive the PRACK even if the PRACK is transmitted through the transmission control protocol.

As the transmitting electronic device <NUM> transmits the PRACK through the transmission control protocol other than the user datagram protocol at operation <NUM>, the corresponding network entity, for example, the proxy call session control function (P-CSCF), can retransmit the PRACK at relatively short intervals. Hence, the receiving electronic device <NUM> can receive the PRACK at operation <NUM> when evolved packet system fallback is completed. For example, the time interval at which the proxy call session control function retransmits the PRACK may be shorter than the time interval at which the transmitting electronic device <NUM> retransmits the PRACK according to the user datagram protocol.

When evolved packet system fallback is completed and before receiving the PRACK, the receiving electronic device <NUM> may retransmit the <NUM> Session Progress, which was last transmitted before performing evolved packet system fallback, using a SIP response message. The SIP response message can be transmitted through the transmission control protocol regardless of its size. The SIP response message may include information indicating that evolved packet system fallback is completed. Upon receiving the <NUM> Session Progress, the transmitting electronic device <NUM> may immediately retransmit the PRACK. Upon detecting information indicating that evolved packet system fallback is completed, the transmitting electronic device <NUM> may immediately retransmit the PRACK. In reply to the PRACK, the receiving electronic device <NUM> may transmit a <NUM> OK using a SIP response message.

<FIG> is a flowchart illustrating an example operation of a transmitting electronic device performing evolved packet system (EPS) fallback according to various embodiments.

In various embodiments of the disclosure, the transmitting electronic device (e.g., transmitting electronic device <NUM> in <FIG>) may be connected to a first communication network. For example, the first communication network may be a <NUM> network.

At operation <NUM>, the transmitting electronic device <NUM> may transmit a message requesting a call connection to an external electronic device (e.g., receiving electronic device <NUM> in <FIG>) using a first transmission protocol.

In various embodiments of disclosure, the message requesting a call connection may be transmitted as a SIP message with Invite. The message requesting a call connection may be transmitted using the first transmission protocol, for example, the user datagram protocol.

In operation <NUM>, the transmitting electronic device <NUM> receives a provisional response message, in reply to the message requesting a call connection, from the external electronic device <NUM> using the first transmission protocol. The provisional response message may be, for example, a SIP response message with <NUM> Session Progress.

At operation <NUM>, the transmitting electronic device <NUM> determines whether the call connection can be supported by the first communication network. If the first communication network cannot support the call connection, the transmitting electronic device <NUM> switches the connection to a second communication network. While the transmitting electronic device <NUM> switches the connection to the second communication network, it may be unable to transmit or receive a message.

In various embodiments of the disclosure, the second communication network may be an evolved packet system (EPS) network. When the transmitting electronic device <NUM> switches the connection from the first communication network to the second communication network, this may be referred to as evolved packet system fallback.

At operation <NUM>, the transmitting electronic device <NUM> may transmit a response message in reply to the received provisional response message using a second transmission protocol.

In various embodiments of the disclosure, the response message for the received provisional response message may be a SIP request message with a PRACK. The response message for the provisional response message may include information indicating that the transmitting electronic device <NUM> has completed communication network switching (or, evolved packet system fallback). For example, the information indicating completion of communication network switching may be included in the header (e.g., warning header) of the SIP request message.

At operation <NUM>, the transmitting electronic device <NUM> may perform the call connection with the receiving electronic device <NUM> using the second communication network.

<FIG> is a flowchart illustrating an example of a receiving electronic device performing evolved packet system (EPS) fallback according to various embodiments.

In various embodiments of the disclosure, the receiving electronic device (e.g., receiving electronic device <NUM> in <FIG>) may be connected to a first communication network. For example, the first communication network may be a <NUM> network.

At operation <NUM>, the receiving electronic device <NUM> may receive a message requesting a call connection from an external electronic device (e.g., transmitting electronic device <NUM> in <FIG>) using a first transmission protocol.

In various embodiments of the disclosure, the message requesting a call connection may be transmitted as a SIP message with Invite. The message requesting a call connection may be transmitted using the first transmission protocol, for example, the user datagram protocol.

At operation <NUM>, the receiving electronic device <NUM> transmits a provisional response message, in reply to the message requesting a call connection, to the external electronic device <NUM> using the first transmission protocol. The provisional response message may be, for example, a SIP response message with <NUM> Session Progress.

At operation <NUM>, the receiving electronic device <NUM> determines whether the call connection can be supported by the first communication network. If the first communication network cannot support the call connection, the receiving electronic device <NUM> switches the connection to a second communication network. While the receiving electronic device <NUM> switches to the second communication network, it may fail to transmit or receive a message.

In various embodiments of the disclosure, the second communication network may be an evolved packet system network. When the receiving electronic device <NUM> switches from the first communication network to the second communication network, this may also be referred to as evolved packet system fallback.

At operation <NUM>, the receiving electronic device <NUM> may retransmit the provisional response message previously transmitted using a second transmission protocol.

In various embodiments of the disclosure, the retransmitted provisional response message may include information indicating that the receiving electronic device <NUM> has completed communication network switching. For example, the information indicating completion of communication network switching may be included in the header (e.g., warning header) of the SIP response message.

At operation <NUM>, the receiving electronic device <NUM> may perform a call connection with the transmitting electronic device <NUM> using the second communication network.

According to various example embodiments of the disclosure, an electronic device connected to a first communication network may include: a communication module comprising communication circuitry; a processor operatively connected to the communication module; and a memory operatively connected to the processor, wherein the memory may store instructions that, when executed, cause the processor to control the electronic device to: transmit a message requesting a call connection through a first transmission protocol to an external electronic device using the communication module; receive a provisional response message for the request through the first transmission protocol from the external electronic device using the communication module; connect, based on the call connection not being supported by the first communication network, to a second communication network using the communication module; transmit a response message for the received provisional response message through a second transmission protocol to the external electronic device using the communication module; and perform the call connection using the connected second communication network.

According to various example embodiments of the disclosure, the response message of the electronic device may further include information indicating that the electronic device has completed communication network switching.

According to various example embodiments of the disclosure, the first transmission protocol of the electronic device may be the user datagram protocol (UDP), and the second transmission protocol may be the transmission control protocol (TCP).

According to various example embodiments of the disclosure, the second transmission protocol of the electronic device may be used to transmit the response message regardless of the size for the response message.

According to various example embodiments of the disclosure, the first communication network of the electronic device may be a fifth generation (<NUM>) network, and the second communication network may be an evolved packet system (EPS) network.

According to various example embodiments of the disclosure, an electronic device connected to a first communication network may include: a communication module comprising communication circuitry; a processor operatively connected to the communication module; and a memory operatively connected to the processor, wherein the memory may store instructions that, when executed, cause the processor to control the electronic device to: receive a message requesting a call connection through a first transmission protocol from an external electronic device using the communication module; transmit a provisional response message for the request through the first transmission protocol to the external electronic device using the communication module; connect, based on the call connection not being supported by the first communication network, to a second communication network using the communication module; retransmit the provisional response message through a second transmission protocol to the external electronic device using the communication module; and perform the call connection using the connected second communication network.

According to various example embodiments of the disclosure, the provisional response message of the electronic device may further include information indicating that the electronic device has completed communication network switching.

According to various example embodiments of the disclosure, the provisional response message may be transmitted to the external electronic device by using the second transmission protocol of the electronic device regardless of the size of the provisional response message.

According to various example embodiments of the disclosure, an operation method of an electronic device connected to a first communication network may include: transmitting a message requesting a call connection to an external electronic device using a first transmission protocol; receiving a provisional response message for the request from the external electronic device using the first transmission protocol; connecting, based on the call connection not being supported by the first communication network, to a second communication network; transmitting a message for the received provisional response message to the external electronic device using a second transmission protocol; and performing the call connection using the connected second communication network.

According to various example embodiments of the disclosure, in the operation method of the electronic device, the response message to be transmitted using the second transmission protocol may further include information indicating that the electronic device has completed communication network switching.

According to various example embodiments of the disclosure, in the operation method of the electronic device, the first transmission protocol may be the user datagram protocol (UDP), and the second transmission protocol may be the transmission control protocol (TCP).

According to various example embodiments of the disclosure, in the operation method of the electronic device, the second transmission protocol may be used to transmit the response message regardless of the size for the response message.

According to various example embodiments of the disclosure, in the operation method of the electronic device, the first communication network may be a fifth generation (<NUM>) network, and the second communication network may be an evolved packet system (EPS) network.

According to various example embodiments of the disclosure, an operation method of an electronic device connected to a first communication network may include: receiving a message requesting a call connection from an external electronic device using a first transmission protocol; transmitting a provisional response message for the request to the external electronic device using the first transmission protocol; connecting, based on the call connection not being supported by the first communication network, to a second communication network; retransmitting the provisional response message to the external electronic device using a second transmission protocol; and performing the call connection using the connected second communication network.

According to various example embodiments of the disclosure, in the operation method of the electronic device, the provisional response message to be retransmitted using the second transmission protocol may further include information indicating that the electronic device has completed communication network switching.

According to various example embodiments of the disclosure, in the operation method of the electronic device, the provisional response message may be transmitted to the external electronic device by using the second transmission protocol regardless of the size of the provisional response message.

In addition, various embodiments are possible.

It should be appreciated that various example embodiments of the present disclosure and the terms used therein are not intended to limit the technological features set forth herein to particular embodiments and include various changes, equivalents, or replacements for a corresponding embodiment. It is to be understood that if an element (e.g., a first element) is referred to, with or without the term "operatively" or "communicatively", as "coupled with," "coupled to," "connected with," or "connected to" another element (e.g., a second element), the element may be coupled with the other element directly (e.g., wiredly), wirelessly, or via a third element.

Wherein, the "non-transitory" storage medium is a tangible device, and may not include a signal (e.g., an electromagnetic wave), but this term does not differentiate between where data is semi-permanently stored in the storage medium and where the data is temporarily stored in the storage medium.

Claim 1:
An electronic device connected to a first communication network (<NUM>), comprising:
a communication module (<NUM>) comprising communication circuitry;
a processor (<NUM>) operatively connected to the communication module (<NUM>); and
a memory (<NUM>) operatively connected to the processor,
wherein the memory (<NUM>) stores instructions that, when executed, cause the processor (<NUM>) to control the electronic device to:
transmit a message requesting a call connection through a first transmission protocol to an external electronic device using the communication module (<NUM>) connected to the first communication network (<NUM>);
receive a provisional response message for the request through the first transmission protocol from the external electronic device using the communication module (<NUM>) connected to the first communication network (<NUM>);
characterised in that the memory further stores instructions that, when executed, cause the processor (<NUM>) to control the electronic device to:
after receiving the provisional response message, switch connection of the communication module (<NUM>) from the first communication network (<NUM>) to a second communication network (<NUM>) based on the call connection not being supported by the first communication network (<NUM>);
transmit a response message for the received provisional response message through a second transmission protocol to the external electronic device using the communication module (<NUM>) connected to the second communication network (<NUM>), wherein the response message further includes information indicating that the electronic device has completed communication network switching; and
perform the call connection using the communication module (<NUM>) connected to the second communication network (<NUM>).