ESIM card and SIM card switching circuit and communication equipment

Abstract

The utility model discloses an ESIM card and SIM card switching circuit and communication equipment. The ESIM card and SIM card switching circuit comprises a main body circuit, an ESIM card, a first SIM card seat, a feedback branch circuit, a first communication branch circuit, a second communication branch circuit, a third communication branch circuit and a change-over switch, the change-over switch comprises a first end, a second end, a third end and a control end; the main body circuit is connected with a first end of the change-over switch through a first communication branch, the first SIM card seat is connected with a second end of the change-over switch through a second communication branch, and the ESIM card is connected with a third end of the change-over switch through a third communication branch; the main body circuit is connected with the first SIM card seat through a feedback branch, when an SIM card is installed on the first SIM card seat, a feedback signal is a third level, a conduction signal is a first level, and the main body circuit is in communication connection with the SIM card on the first SIM card seat; and when the first SIM card seat is not provided with the SIM card, the feedback signal is a fourth level, the conduction signal is a second level, and the main body circuit is in communication connection with the ESIM card. Automatic switching from the ESIM card to the SIM card application is realized, and manual setting is not needed.

Description

Technical Field

[0001] This application relates to the field of communication equipment technology, specifically to an ESIM card and SIM card switching circuit and communication equipment. Background Technology

[0002] ESIM cards are being widely used in communication devices to replace the traditional removable SIM card. However, ESIM cards have not completely replaced SIM cards; therefore, SIM cards and ESIM cards may coexist on the same communication device. Currently, when both SIM cards and ESIM cards are present on a communication device, manual switching is required when switching from ESIM to SIM; automatic switching is not possible. Utility Model Content

[0003] This application provides an ESIM card and SIM card switching circuit and communication device. The technical problem to be solved is how to enable automatic switching between a SIM card and an ESIM card existing on the same communication device.

[0004] According to a first aspect of this application, one embodiment provides an ESIM card and SIM card switching circuit, including: a main circuit, an ESIM card, a first SIM card holder, a feedback branch, a first communication branch, a second communication branch, a third communication branch, and a switching switch;

[0005] The switching switch includes a first terminal, a second terminal, a third terminal, and a control terminal; the main circuit is connected to the first terminal of the switching switch via the first communication branch, the first SIM card slot is connected to the second terminal of the switching switch via the second communication branch, and the ESIM card is connected to the third terminal of the switching switch via the third communication branch. The switching switch is used to connect its first terminal and second terminal to connect the first communication branch and the second communication branch when the control terminal's conduction signal is at a first level, and to connect its first terminal and third terminal to connect the first communication branch and the third communication branch when the control terminal's conduction signal is at a second level.

[0006] The first SIM card slot is used to be triggered when a SIM card is installed to maintain the feedback signal of the feedback branch at the third level; otherwise, it maintains the feedback signal of the feedback branch at the fourth level.

[0007] The main circuit is connected to the first SIM card slot through the feedback branch. In response to the feedback signal of the feedback branch being at the third level, the main circuit maintains the conduction signal at the first level. In response to the feedback signal of the feedback branch being at the fourth level, the main circuit maintains the conduction signal at the second level.

[0008] Optionally, it also includes: a fourth communication branch and a second SIM card slot;

[0009] The main circuit is also connected to the second SIM card slot via the fourth communication branch, so that the main circuit and the second SIM card slot can communicate with each other.

[0010] Optionally, the switching switch includes: a first chip and a first resistor;

[0011] Pins 1, 5, 9, and 13 of the first chip are connected to the first SIM card slot; pins 2, 4, 8, and 12 of the first chip are connected to the main circuit; pins 15, 3, 7, and 11 of the first chip are connected to the ESIM card; pin 14 of the first chip is connected to the first power supply; and pin 2 of the first chip is grounded through one end of the first resistor.

[0012] Specifically, pin 2 of the first chip is used to receive a conduction signal; the connection between pins 4, 8, and 12 of the first chip and the main circuit forms the first communication branch; the connection between pins 5, 9, and 13 of the first chip and the first SIM card slot forms the second communication branch; and the connection between pins 15, 3, 7, and 11 of the first chip and the ESIM card forms the third communication branch.

[0013] Optionally, the switching switch further includes a first filtering unit, which is connected to the connection line between pin 14 of the first chip and the first power supply.

[0014] Optionally, the first filtering unit includes a first capacitor, one end of which is connected to pin 14 of the first chip, and the other end of which is grounded.

[0015] Optionally, the first SIM card slot includes: a second chip and a second resistor;

[0016] The G16 pin of the second chip is connected to the main circuit, and the connection between the G16 pin of the second chip and the main circuit forms the feedback branch.

[0017] The second chip's G1, G2, G3, G4, G5, G6, G7, G8, G9, G10, G11, G18, and G19 pins are grounded. The second chip's G13 pin is connected to the first chip's pin 11. The second chip's G12 pin is connected to the first chip's pin 9. The second chip's G14 pin is connected to the first chip's pin 5. The second chip's G17 pin is connected to the first chip's pin 1.

[0018] Among them, pin G17 of the second chip is the power supply pin of the second chip, and pin G16 of the second chip is used to output feedback signals.

[0019] Optionally, the first SIM card slot further includes a second filtering unit, which is connected to the connection line between pin G17 of the second chip and pin 1 of the first chip.

[0020] Optionally, the second filter unit includes a second capacitor, one end of which is connected to pin G17 of the second chip, and the other end of which is grounded.

[0021] Optionally, the ESIM card includes a third chip, with pin 1 of the third chip grounded, pin 3 of the third chip connected to pin 11 of the first chip, pin 6 of the third chip connected to pin 7 of the first chip, pin 7 of the third chip connected to pin 3 of the first chip, and pin 8 of the third chip connected to a second power supply.

[0022] Among them, pin 8 of the third chip is the power supply pin of the third chip.

[0023] According to a second aspect of this application, one embodiment provides a communication device, including: a printed circuit board and an ESIM card and SIM card switching circuit as described above, wherein the ESIM card and SIM card switching circuit is disposed on the printed circuit board.

[0024] This invention provides an ESIM card to SIM card switching circuit and communication device. When a SIM card is installed in the first SIM card slot, the first SIM card slot is triggered to maintain the feedback signal of the feedback branch at the third level, and the main circuit maintains the conduction signal at the first level. At this time, the first communication branch and the second communication branch are connected, and the main circuit communicates with the SIM card in the first SIM card slot. When no SIM card is installed in the first SIM card slot, the first SIM card slot is triggered to maintain the feedback signal of the feedback branch at the fourth level, and the main circuit maintains the conduction signal at the second level. At this time, the first communication branch and the third communication branch are connected, and the main circuit communicates with the ESIM card. Therefore, when a SIM card is installed in the first SIM card slot, the main circuit can automatically switch to communicating with the SIM card in the first SIM card slot; when no SIM card is installed in the first SIM card slot, the main circuit can automatically switch to communicating with the ESIM card, realizing automatic switching from ESIM card to SIM card application without manual setting. Attached Figure Description

[0025] Figure 1This is a block diagram illustrating the principle of the ESIM card and SIM card switching circuit.

[0026] Figure 2 This is a circuit diagram of a switching switch in one embodiment;

[0027] Figure 3 This is a circuit diagram of the first SIM card slot in one embodiment;

[0028] Figure 4 This is a circuit diagram of an ESIM card in one embodiment.

[0029] Reference numerals: 10, Main circuit; 20, ESIM card; 30, First SIM card slot; 301, Second filter unit; 40, Feedback branch; 50, First communication branch; 60, Second communication branch; 70, Third communication branch; 80, Switch; 801, First filter unit; 90, Fourth communication branch; 100, Second SIM card slot; R1, First resistor; R2, Second resistor; C1, First capacitor; C2, Second capacitor; U1, First chip; U2, Second chip; U3, Third chip. Detailed Implementation

[0030] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0031] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments, and the operational steps involved in each embodiment can also be rearranged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the specification and drawings are only for clearly describing a particular embodiment and do not imply that they represent the necessary components and / or order.

[0032] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0033] like Figure 1 The diagram shown is a schematic block diagram of an ESIM card and SIM card switching circuit. Please refer to it. Figure 1 The ESIM card and SIM card switching circuit may include a main circuit 10, an ESIM card 20, a first SIM card holder 30, a feedback branch 40, a first communication branch 50, a second communication branch 60, a third communication branch 70, and a switching switch 80.

[0034] The switching switch 80 includes a first terminal, a second terminal, a third terminal, and a control terminal. The main circuit 10 is connected to the first terminal of the switching switch 80 through the first communication branch 50. The first SIM card holder 30 is connected to the second terminal of the switching switch 80 through the second communication branch 60. The ESIM card 20 is connected to the third terminal of the switching switch 80 through the third communication branch 70. The switching switch 80 is used to connect its first terminal and second terminal to make the first communication branch 50 and the second communication branch 60 connected when the conduction signal of the control terminal is at the first level, and to connect its first terminal and third terminal to make the first communication branch 50 and the third communication branch 70 connected when the conduction signal of the control terminal is at the second level.

[0035] The first SIM card slot 30 is used to be triggered when a SIM card is installed to maintain the feedback signal of the feedback branch 40 at the third level, and otherwise to maintain the feedback signal of the feedback branch 40 at the fourth level.

[0036] The main circuit 10 is connected to the first SIM card slot 30 through the feedback branch 40. In response to the feedback signal of the feedback branch 40 being at the third level, the main circuit 10 maintains the conduction signal at the first level. In response to the feedback signal of the feedback branch 40 being at the fourth level, the main circuit 10 maintains the conduction signal at the second level.

[0037] In a specific application of this ESIM card and SIM card switching circuit, when a SIM card is installed in the first SIM card slot 30, the feedback signal of the feedback branch 40 is maintained at a low level, that is, the third level is a low level signal. At this time, the main circuit 10 outputs a low level signal to the control terminal of the switching switch 80, so that the first terminal and the second terminal of the switching switch 80 are connected, thereby connecting the first communication branch 50 and the second communication branch 60. The main circuit 10 communicates with the SIM card in the first SIM card slot 30. In other words, when the first level is a low level signal, the main circuit 10 communicates with the SIM card in the first SIM card slot 30.

[0038] Conversely, when no SIM card is installed in the first SIM card slot 30, the feedback signal of the feedback branch 40 is maintained at a high level. That is, the fourth level is a high-level signal. At this time, the main circuit 10 outputs a high-level signal to the control terminal of the switch 80, causing the first and third terminals of the switch 80 to conduct, thereby connecting the first communication branch 50 and the third communication branch 70. The main circuit 10 then communicates with the ESIM card 20. In other words, when the second level is a high-level signal, the main circuit 10 communicates with the ESIM card 20. Of course, when the feedback signal of the feedback branch 40 remains unchanged, the conduction signal maintained by the main circuit 10 also remains unchanged.

[0039] Therefore, when a SIM card is installed in the first SIM card slot 30, the main circuit 10 can automatically switch to communication with the SIM card in the first SIM card slot 30. When no SIM card is installed in the first SIM card slot 30, the main circuit 10 can automatically switch to communication with the ESIM card 20. This enables automatic switching from ESIM card 20 to SIM card application without manual settings, thus improving switching efficiency.

[0040] The main circuit 10 can be, but is not limited to, a circuit built with a CPU (Central Processing Unit) as the core device that can realize the above functions. Those skilled in the art can determine the specific circuit structure of the main circuit 10 according to actual needs, and no further restrictions are imposed here.

[0041] For further information, please continue to refer to [link / reference]. Figure 1 The ESIM card and SIM card switching circuit also includes a fourth communication branch 90 and a second SIM card slot 100. The main circuit 10 communicates with the SIM card on the second SIM card slot 100 through the fourth communication branch 90.

[0042] In practical applications, a SIM card is installed in the second SIM card slot 100, and this SIM card communicates directly with the main circuit 10. In other words, regardless of whether a SIM card is installed in the first SIM card slot 30, the main circuit 10 communicates with the SIM card in the second SIM card slot 100.

[0043] Therefore, when an ESIM card 20 is installed in the first SIM card slot 30, the ESIM card and SIM card switching circuit can realize communication between the two cards (the SIM card in the first SIM card slot 30 and the SIM card in the second SIM card slot 100). When no ESIM card 20 is installed in the first SIM card slot 30, the ESIM card and SIM card switching circuit can realize simultaneous communication between the SIM card (the SIM card in the second SIM card slot 100) and the ESIM card 20, making the application of the ESIM card and SIM card switching circuit more flexible.

[0044] In some embodiments, please refer to Figure 2 The switching switch 80 may include a first chip U1 and a first resistor R1; pins 1, 5, 9, and 13 of the first chip U1 are connected to the first SIM card slot 30; pins 2, 4, 8, and 12 of the first chip U1 are connected to the main circuit 10; pins 15, 3, 7, and 11 of the first chip U1 are connected to the ESIM card 20; pin 14 of the first chip U1 is connected to the first power supply; and pin 2 of the first chip U1 is connected to the first... One end of resistor R1 is grounded; pin 2 of the first chip U1 is used to receive the conduction signal; the connection between pins 4, 8, and 12 of the first chip U1 and the main circuit 10 forms the first communication branch 50; the connection between pins 5, 9, and 13 of the first chip U1 and the first SIM card slot 30 forms the second communication branch 60; the connection between pins 15, 3, 7, and 11 of the first chip U1 and the ESIM card 20 forms the third communication branch 70.

[0045] Specifically, the first chip U1 can be, but is not limited to, the BTC4567 chip of the BROADCHIP (Guangxin Electronics) brand. The first resistor R1 is a pull-down resistor. When a SIM card is installed in the first SIM card slot 30, pin 2 of the first chip U1 can receive a low-level signal. At this time, the first communication branch 50 is connected to the second communication branch 60. That is, the main circuit 10 can communicate with the SIM card in the first SIM card slot 30 through pins 4, 8, 12, 5, 9, and 13 of the first chip U1.

[0046] When a SIM card is installed in the first SIM card slot 30, pin 2 of the first chip U1 can receive a high-level signal. At this time, the first communication branch 50 is connected to the third communication branch 70. That is, the main circuit 10 can communicate with the ESIM card 20 through pins 4, 8, 12, 15, 3, 7 and 11 of the first chip U1.

[0047] For further information, please continue to refer to [link / reference]. Figure 2The switching switch 80 also includes a first filtering unit 801, which is connected to the connection line between pin 14 of the first chip U1 and the first power supply. The first power supply can be an external power supply, and its specific setting can be based on the actual required supply voltage; details will not be elaborated here.

[0048] Specifically, the first filtering unit 801 may include a first capacitor C1, one end of which is connected to pin 14 of the first chip U1, and the other end of which is grounded. The first capacitor C1 filters out interference signals in the power supply voltage output from the first power supply to pin 14 of the first chip U1.

[0049] In some embodiments, when power is drawn to the second SIM card slot 100, power can be drawn through pin 16 of the first chip U1. When power is drawn to the first SIM card slot 30, power can be drawn through pin 1 of the first chip U1.

[0050] In some embodiments, please refer to Figure 3 The first SIM card holder 30 may include a second chip U2 and a second resistor R2; pin G16 of the second chip U2 is connected to the main circuit 10, and the connection between pin G16 of the second chip U2 and the main circuit 10 forms a feedback branch 40; pins G1, G2, G3, G4, G5, G6, G7, G8, G9, G10, G11, G18, and G19 of the second chip U2 are grounded; pin G13 of the second chip U2 is connected to pin 11 of the first chip U1; pin G12 of the second chip U2 is connected to pin 9 of the first chip U1; pin G14 of the second chip U2 is connected to pin 5 of the first chip U1; and pin G17 of the second chip U2 is connected to pin 1 of the first chip U1; wherein pin G17 of the second chip U2 is the power supply pin of the second chip, and pin G16 of the second chip U2 is used to output a feedback signal.

[0051] Specifically, the second chip U2 can be, but is not limited to, the S258-OB08B23F from Hongri Technology; for example, the second chip U2 can also be the S81-1B08F15A chip from Jiehuang Electronics. The second resistor R2 is a pull-up resistor. Pin G17 of the second chip U2 is connected to pin 1 of the first chip U1, and is powered through pin 1 of the first chip U1. The connection between pin G13 of the second chip U2 and pin 11 of the first chip U1, the connection between pin G12 of the second chip U2 and pin 9 of the first chip U1, and the connection between pin G14 of the second chip U2 and pin 5 of the first chip U1 form the second communication branch 60.

[0052] For further information, please continue to refer to [link / reference]. Figure 3The first SIM card holder 30 also includes a second filtering unit 301, which is connected to the connection between pin G17 of the second chip and pin 1 of the first chip U1.

[0053] Specifically, the second filtering unit 301 may include a second capacitor C2, one end of which is connected to pin G17 of the second chip U2, and the other end of which is grounded. The interference signal in the power supply voltage output to pin G17 of the second chip U2 is filtered out through the second capacitor C2.

[0054] In some embodiments, please refer to Figure 4 The ESIM card 20 may include a third chip U3, with pin 1 of the third chip U3 grounded, pin 3 of the third chip U3 connected to pin 11 of the first chip U1, pin 6 of the third chip U3 connected to pin 7 of the first chip U1, pin 7 of the third chip U3 connected to pin 3 of the first chip U1, and pin 8 of the third chip U3 connected to a second power supply; wherein, pin 8 of the third chip U3 is the power supply pin of the third chip U3.

[0055] Specifically, the third chip U3 can be, but is not limited to, a chip with the model number ST33G1M2; for example, the third chip U3 can also be a chip with the model number ST33I1M2. The second power supply can be an external power supply, and the specific settings can be configured according to the actual required power supply voltage, which will not be elaborated on here. The connection between pin 3 of the third chip U3 and pin 11 of the first chip U1, the connection between pin 6 of the third chip U3 and pin 7 of the first chip U1, and the connection between pin 7 of the third chip U3 and pin 3 of the first chip U1 form the third communication branch 70.

[0056] In some embodiments, the present invention also provides a communication device, which may include a printed circuit board and an ESIM card and SIM card switching circuit as described above, wherein the ESIM card and SIM card switching circuit is disposed on the printed circuit board.

[0057] The communication device can be, but is not limited to, mobile phones, tablets, laptops, smartwatches, and other communication devices. The specific implementation of the ESIM card and SIM card switching circuit within the communication device is as described in the aforementioned embodiment, and will not be repeated here.

[0058] In summary, this utility model provides an ESIM card and SIM card switching circuit and communication device, which has the following beneficial effects:

[0059] When a SIM card is installed in the first SIM card slot 30, the first SIM card slot 30 is triggered to maintain the feedback signal of the feedback branch 40 at the third level, and the main circuit 10 maintains the conduction signal at the first level. At this time, the first communication branch 50 and the second communication branch 60 are connected, and the main circuit 10 communicates with the SIM card in the first SIM card slot 30. When no SIM card is installed in the first SIM card slot 30, the first SIM card slot 30 is triggered to maintain the feedback signal of the feedback branch 40 at the fourth level, and the main circuit 10 maintains the conduction signal at the second level. At this time, the first communication branch 50 and the third communication branch 70 are connected, and the main circuit 10 communicates with the ESIM card 20. Therefore, when a SIM card is installed in the first SIM card slot 30, the main circuit 10 automatically switches to communicate with the SIM card in the first SIM card slot 30; when no SIM card is installed in the first SIM card slot 30, the main circuit 10 automatically switches to communicate with the ESIM card 20. This achieves automatic switching between ESIM card 20 and SIM card applications without manual configuration.

[0060] The above-described specific examples are for illustrative purposes only and are not intended to limit the scope of this invention. Those skilled in the art to which this invention pertains can make various simple deductions, modifications, or substitutions based on the concept of this invention.

Claims

1. An ESIM card and SIM card switching circuit, characterized by, include: The main circuit, ESIM card, first SIM card slot, feedback branch, first communication branch, second communication branch, third communication branch, and switching switch; The switching switch includes a first terminal, a second terminal, a third terminal, and a control terminal; the main circuit is connected to the first terminal of the switching switch via the first communication branch, the first SIM card slot is connected to the second terminal of the switching switch via the second communication branch, and the ESIM card is connected to the third terminal of the switching switch via the third communication branch. The switching switch is used to connect its first terminal and second terminal to connect the first communication branch and the second communication branch when the control terminal's conduction signal is at a first level, and to connect its first terminal and third terminal to connect the first communication branch and the third communication branch when the control terminal's conduction signal is at a second level. The first SIM card slot is used to be triggered when a SIM card is installed to maintain the feedback signal of the feedback branch at the third level; otherwise, it maintains the feedback signal of the feedback branch at the fourth level. The main circuit is connected to the first SIM card slot through the feedback branch. In response to the feedback signal of the feedback branch being at the third level, the main circuit maintains the conduction signal at the first level. In response to the feedback signal of the feedback branch being at the fourth level, the main circuit maintains the conduction signal at the second level.

2. The ESIM card and SIM card switching circuit of claim 1, wherein, It also includes: a fourth communication branch and a second SIM card slot; The main circuit is also connected to the second SIM card slot via the fourth communication branch, so that the main circuit and the second SIM card slot can communicate with each other.

3. The ESIM card and SIM card switching circuit of claim 1 or 2, wherein, The switching switch includes: a first chip and a first resistor; Pins 1, 5, 9, and 13 of the first chip are connected to the first SIM card slot; pins 2, 4, 8, and 12 of the first chip are connected to the main circuit; pins 15, 3, 7, and 11 of the first chip are connected to the ESIM card; pin 14 of the first chip is connected to the first power supply; and pin 2 of the first chip is grounded through one end of the first resistor. Specifically, pin 2 of the first chip is used to receive a conduction signal; the connection between pins 4, 8, and 12 of the first chip and the main circuit forms the first communication branch; the connection between pins 5, 9, and 13 of the first chip and the first SIM card slot forms the second communication branch; and the connection between pins 15, 3, 7, and 11 of the first chip and the ESIM card forms the third communication branch.

4. The ESIM card and SIM card switching circuit of claim 3, wherein, The switching switch further includes a first filtering unit, which is connected to the connection line between pin 14 of the first chip and the first power supply.

5. The ESIM card and SIM card switching circuit of claim 4, wherein, The first filtering unit includes a first capacitor, one end of which is connected to pin 14 of the first chip, and the other end of which is grounded.

6. The ESIM card and SIM card switching circuit of claim 3, wherein, The first SIM card slot includes: a second chip and a second resistor; The G16 pin of the second chip is connected to the main circuit, and the connection between the G16 pin of the second chip and the main circuit forms the feedback branch. The second chip's G1, G2, G3, G4, G5, G6, G7, G8, G9, G10, G11, G18, and G19 pins are grounded. The second chip's G13 pin is connected to the first chip's pin 11. The second chip's G12 pin is connected to the first chip's pin 9. The second chip's G14 pin is connected to the first chip's pin 5. The second chip's G17 pin is connected to the first chip's pin 1. Among them, pin G17 of the second chip is the power supply pin of the second chip, and pin G16 of the second chip is used to output feedback signals.

7. The ESIM card and SIM card switching circuit of claim 6, wherein, The first SIM card slot also includes a second filtering unit, which is connected to the connection between pin G17 of the second chip and pin 1 of the first chip.

8. The ESIM card and SIM card switching circuit as described in claim 7, characterized in that, The second filter unit includes a second capacitor, one end of which is connected to pin G17 of the second chip, and the other end of which is grounded.

9. The ESIM card and SIM card switching circuit of claim 3, wherein, The ESIM card includes a third chip, with pin 1 of the third chip grounded, pin 3 of the third chip connected to pin 11 of the first chip, pin 6 of the third chip connected to pin 7 of the first chip, pin 7 of the third chip connected to pin 3 of the first chip, and pin 8 of the third chip connected to a second power supply. Among them, pin 8 of the third chip is the power supply pin of the third chip.

10. A communication device, characterized by include: The printed circuit board and the ESIM card and SIM card switching circuit as described in any one of claims 1-9, wherein the ESIM card and SIM card switching circuit is disposed on the printed circuit board.

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