It is critical to understand the current network landscape before purchasing:

: Prioritize sellers offering at least a 30-day return policy to protect against hardware "duds".

: Sprint's legacy 3G CDMA network has been shut down; avoid very old refurbished Sprint phones (like those from the 2010 era) as they can no longer be used on any modern network.

: Most late-model Sprint devices (those with LTE or 5G) will work on the T-Mobile network.