Typical protocol for trading in your phone.

[legend018]

I'm thinking more about the future, would rather have an idea now then be wondering when it's about to happen.
Say I trade in my phone.  The company I deal with for my cell phone does stuff like that where you can trade in your phone to get value off of a newer phone.  If you have a wallet on there, lets assume it's a small amount but an amount never the less.
You make sure you have the proper backup, remove it completely before sending it over as well as any other programs you might use such as the authenticator and then just reinstall everything once you got your new phone?

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[SureLockLoans]

As long as you have a back up of the wallet.dat then you are fine and can use that on any device no matter the operating system. It's always recommended to make a secure copy of your private key too. Like writing it down on a piece of paper and storing that in a safe.

Then if you do lose the wallet.dat you can still access your bitcoins via the private key.

[legend018]

As long as you have a back up of the wallet.dat then you are fine and can use that on any device no matter the operating system. It's always recommended to make a secure copy of your private key too. Like writing it down on a piece of paper and storing that in a safe.

Then if you do lose the wallet.dat you can still access your bitcoins via the private key.

The wallet.dat is more for Computers though not cell phones right? For example currently I have mycelium on my phone and I did the backup.  I haven't found any information on if I'm suppose to keep doing a backup or if I'm suppose to do anything else, but that's research I'll have to do. 

[xdrpx]

Before the time arrives to trade your phone, make sure you do few thing. Firstly, backup your mycelium seed and write it down in a paper. This can later be imported on the  mycelium installed onto your new device. Then, if you have an android phone make sure you write 0's to your SD card and phone by using Secure Eraser, which would wipe out most of the data and then factory reset your phone.

If you're using your iPhone, i'm sure encryption is enabled by default, so Reset and Erase all content and settings should be good enough and safe to assure that everything is gone. Also since mobile devices are a more secure platform to run wallets, it's safe to assume that once a factory reset is done, your data is gone forever.

[harizen]

As long as you have a back up of the wallet.dat then you are fine and can use that on any device no matter the operating system. It's always recommended to make a secure copy of your private key too. Like writing it down on a piece of paper and storing that in a safe.

Then if you do lose the wallet.dat you can still access your bitcoins via the private key.

The wallet.dat is more for Computers though not cell phones right? For example currently I have mycelium on my phone and I did the backup.  I haven't found any information on if I'm suppose to keep doing a backup or if I'm suppose to do anything else, but that's research I'll have to do. 

Most bitcoin applications on Mobile especially wallets have an option of backup either mnemonic phrase or 12 words seeds. In case of web wallets applications, logins credentials is the one that you take note. I know you already understand this based on your posting.

If you think you backed it all properly then you are good to go to have a new phone. You can also test this by borrowing an extra phone or much better if you have an extra phone to see if your backup is working.

[DannyHamilton]

The wallet.dat is more for Computers though not cell phones right?

Correct.  The ONLY wallets that I know of that use a "wallet.dat" are Bitcoin Core and the many full node implementations that were created by forking the Bitcoin Core source code.

For example currently I have mycelium on my phone and I did the backup.  I haven't found any information on if I'm suppose to keep doing a backup or if I'm suppose to do anything else, but that's research I'll have to do. 

So far, you've received a lot of mediocre (or horrible) advice from sig ad users that care more about increasing their post count than actually helping.

What you need to do in order to back up your wallet will depend on the wallet that you are using.  Each wallet has it's own backup requirements, and it is your responsibility to understand how to properly use whatever software you've chosen to use.

You've mentioned Mycelium.  In that case, you only need to back up the seed words once. All the addresses and private keys that Mycelium generates are all generated from that set of seed words. You will be able to recover the entire wallet at any time you need to by using the seed words.  You can store as many copies of those seed words as you like, but it is your responsibility to make sure of two things...
1.  You will always be able to find a readable copy of the seed words when you need to.
2.  Nobody else will have access to your seed words.

If you fail at responsibility #1, then you may find yourself in a situation where your bitcoins have not been taken, but you can no longer access them.  They will be permanently lost to the entire bitcoin system.

If you fail at responsibility #2, then you may find yourself in a situation where someone else spends your bitcoins without your permission.

Note that, if you install a new Mycelium wallet and don't build it from a set of seed words, then it will generate a new set of seed words specifically for that wallet.  In that case, you would have separate wallets each using Mycelium and each with their own set of seed words to keep track of.

Creating a backup of your wallet before trading in your phone takes care of responsibility #1.  However, it does NOT take care of responsibility #2.  There is a possibility that whomever receives your phone when you trade it in might try to extract your wallet from the phone without your knowledge or permission.  There are a few possible ways to manage this risk.

1. Prior to trading in, you could create a temporary wallet on a different device (some other phone, or computer), and create a backup of it.  Then create a transaction to send ALL of your bitcoins from your phone to this temporary wallet.  Now when you trade in your phone. if someone succeeds in extracting your wallet from your phone, it won't matter since there aren't any bitcoins associated with that wallet any longer.  Then after you set up new wallet on your new phone AND create a backup of that new wallet, you could send your bitcoins from your temporary wallet to this new phone wallet.

2.  You could learn how to securely wipe all data from the phone before trading it in (the process may vary from phone to phone, so make sure you understand the proper process for your specific phone).  This method is fast and easy. It also avoids the transaction fees of sending from your old wallet to a temp wallet, and then the transaction fees of sending from the temp wallet to a new wallet (assuming you set up your new wallet on the new phone by recovering from your seed words).  However, there is a risk that the wipe won't be as secure as you think it is, or that you don't understand the proper process to implementing such a wipe.