You can give the following written devices in Trade-in: ⇨ Smartphones ⇨ Smartwatches ⇨ Normal mobile phone ⇨ Tablet ⇨ Hotspot connecting devices ⇨ Netbook ⇨ Prepaid phones which work on a 3G network and have been active for at least 6 months.  ⇨ Prepaid phones which work on a 4G network and have been active for at least 6 months plus the payment for the very first month has been done.  So, you can Trade- in these devices if you want to.