This depends on the type of micro spy you use. If you have a GSM microspion, you will need a phone subscription to use it. This type of micro-espion uses a SIM card to transmit the recordings to an external device. You will need to subscribe to a mobile operator and insert the SIM card in the micro-espion. If you have a wireless microphone, you may not need a telephone subscription. This type of micro-espion can transmit the recordings to an external device via a wireless connection, such as Bluetooth or Wi-Fi. It is important to read the product specifications to find out if it requires a phone subscription before buying it. It is also important to comply with local privacy and surveillance laws when using a micro-spion.