The cordless handset with charging plate and module kit, 50005713, splits into:
The cordless headset with charging cradle and module kit, 50005714, splits into:
The serial numbers can be found as follows:
50005402 - The bar code sticker is on the outside of module
50005403 - Open up the handset to see the serial number
50005404 - Remove the charging cradle from the desktop phone to see the serial number - you'll need to remove the screws
The serial number format for older equipment is 5 letters and 4 numbers beginning with FS. The newer ones are a mixture of numbers and letters e.g. 1U4FS11290G5.