An electronic device connected to a first communication network, comprising: 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; characterised in that 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. 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; characterised in that 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. 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; characterised in that 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. 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.