Install SIM card and activate new phone before or after using Samsung Smart Switch?

You can activate the new phone before using Smart Switch.  In fact, you can use Smart Switch months later if you wish (not that you'd want to).

I assume you are activating a new phone which will deactivate the old one in the process.  That's not an issue as the old phone is still working, just no longer getting a cell signal.  All data on the phone will still be there to transfer - including texts and account information.  You may be prompted to input any needed passwords along the way.

If using Smart Switch with a USB cable (and one end having the OTG USB dongle attached per instructions), the new phone will only see the old phone to pull stuff from anyway.  If using the wi-fi, then both phones will need Smart Switch running to find each other. I actually forget if you have to run Smart Switch on the old phone when using the USB cable, or it may start it up automatically.

Either way, whether the old phone has an active SIM or not won't matter.  

Thank you Joel!  

Hi there @Gamenole, we're here to assist with installing SIM card using Samsung Smart Switch.

Thank you, @joeldf for that great input as you are correct! When switching to Galaxy, you don't have to say goodbye to your old stuff. The data and content you were using before - your photos, videos, contacts, calendar events, notes and device settings get to stay with you on your new Galaxy.

If you purchased your phone online, you may need to activate your new phone and SIM card before use. Below we have helpful tips to make this an easy process:

1. Insert the SIM card - You can also find this information in your user manual.
2. Go to att.com/activations.
3. Select Activate your device for AT&T wireless device.
4. Enter the required information.
5. Select Continue.
6. Follow the prompts to complete your activation.

Once you are done activating your device, you can log in to your myAT&T account where you can check information like billing, features, upgrade options, and much more!

We hope this information works out for you.

Ashley, AT&T Community Specialist 

Thank you Joel & Ashley for your help, I did the transfer myself this evening after activating my new phone and everything went perfectly.

Thanks for the update, @Gamenole.

We're glad that you were able to resolve your inquiries and get your new device activated. 

We appreciate your business with AT&T an thanks for reaching out to the AT&T Community Forums. 

Lynn, AT&T Community Specialist