Mobile Phones Iphone 4 unlocked

[cosso1]

I have an iphone 4 that I would like to sell on, as now my daughter has a new phone.
Originally the phone was locked to Vodafone and I had it unlocked through iTunes and it has been used on T-Mobile for the past year, I have now erased and deleted all data ready to sell, will the phone still be unlocked for all networks or will it only work on T-Mobile, as this was the last sim inserted after unlock?
I don't want to sell as open to all networks, if it's not.
Thanks

 

[Kryton]

If you have had it factory unlocked by vodafone then it will remain unlocked even after updates , restores and erasing data/restoring settings.

 

[cosso1]

If you have had it factory unlocked by vodafone then it will remain unlocked even after updates , restores and erasing data/restoring settings.

I think that's what I did, as I had to get in touch with Vodafone, before iTunes could do what it needed to do. Also it has took at least one update while my daughters been using it and everything was fine.