Sold iPhone 4s unlocked couple questions

[bobright]

So I am about to send off my iPhone which I just sold. I was wondering what is the best way to send it off and make sure everything on it is wiped clean.

Should I restore with my sim card in it, then pull the sim and send it off? Or should I restore WITHOUT the sim and then simply send off?

Does doing so one way or the other effect the unlock in any way, or once its unlocked (which I already did) it is unlocked for good?

 

[Chopstick217]

So I am about to send off my iPhone which I just sold. I was wondering what is the best way to send it off and make sure everything on it is wiped clean.

Should I restore with my sim card in it, then pull the sim and send it off? Or should I restore WITHOUT the sim and then simply send off?

Does doing so one way or the other effect the unlock in any way, or once its unlocked (which I already did) it is unlocked for good?

Im assuming the phone is unlocked via IMEI number. If that is the case, then the unlock is permanent. As for wiping data, I just go into settings, general, rest and "erase all content and settings." That should remove everything from your phone.