I have two old CDMA phones (Google Nexus L700s, if that matters) that I used to use with Ting. Both have been replaced with newer GSM phones and our old phone numbers were moved over to the SIMs in our new phones (1 month and 6 months ago). The new phones have been working great and we've had no problems making/receiving calls on them. The old phones are listed as inactive on my Ting account.
I would like to donate the old phones to a local charity, and have deleted all my old data and factory reset the phones. However, when I look in the phones' Settings > About phone > Status, it still shows Service state "In service" and "My phone number" still shows our two phone numbers, which had been moved to the new phones months ago.
My concern is having our phone numbers still visible on the old phones. Is that a security concern? Is there any risk my Ting service could be interrupted if someone tried to reactivate these phones on some other Sprint or Sprint-compatible MVNO?
The phones still work and I'd hate to destroy them if somebody else could use them, but I don't want to take a chance my Ting service on my new phones could get messed up.