Provided is a system and method for recognizing a user's speech. A method, performed by a server, of providing a text string for a speech signal input to a device includes: receiving, from the device, an encoder output value derived from an encoder of an end-to-end automatic speech recognition (ASR) model included in the device; identifying a domain corresponding to the received encoder output value; selecting a decoder corresponding to the identified domain from among a plurality of decoders of an end-to-end ASR model included in the server; obtaining a text string from the received encoder output value using the selected decoder; and providing the obtained text string to the device.