If the device you're attempting to list requires that a ESN or serial number be provided, the way to locate this can differ quite a bit from device to device. For all cellular devices, Swappa requires that the device's ESN be provided, and this is usually in the form of an IMEI. For devices that only support Wi-Fi connections, the device's serial number is requested instead.

Here are some support page resources from various manufacturer websites to assist in locating the ESN or serial number if needed:

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