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It took me two hours on the phone with Verizon to figure this out. Steps to activate the new 5G SIM:

1. turn off old phone
(make sure Wifi is disconnected - I had to unplug my router)
2. shut down new phone
3. remove SIM card from new phone, then put the SIM back in
4. restart new phone
5. activate

For some reason you need to power off, take the SIM out, and power on again for the phone to "reset" the activation sequence, even if they try to activate on the Verizon end. I was the first person with a 12 that the V rep had talked to, so it took a while to troubleshoot.

It works great now!

For me I forgot to turn off Wi-Fi. All I did was turn off the phone normally, After of course logging out of iCloud and turning off Find my Phone, removed the Sim card from the Xs and placed it in the 12, then turned on the 12 and it started of the activation. I am on Verizon and I thought your method was the method I saw posted, but failed to follow my own reading. Don’t know what happened, but everything worked for me. Transferred everything over from my old phone, which did not take that long, though I did not have that much stuff on the previous phone. Interesting that some have different experiences over others when activating.
 
For me I forgot to turn off Wi-Fi. All I did was turn off the phone normally, After of course logging out of iCloud and turning off Find my Phone, removed the Sim card from the Xs and placed it in the 12, then turned on the 12 and it started of the activation. I am on Verizon and I thought your method was the method I saw posted, but failed to follow my own reading. Don’t know what happened, but everything worked for me. Transferred everything over from my old phone, which did not take that long, though I did not have that much stuff on the previous phone. Interesting that some have different experiences over others when activating.

I did that too. But Verizon said don’t. At least one rep said that.

Did you get a pop up that said you took out the 5g sim?
 
I did that too. But Verizon said don’t. At least one rep said that.

Did you get a pop up that said you took out the 5g sim?

The Sim card I got was a newly obtained card from Verizon a few days ago and slipped it in my iPhone XS before putting it my iPhone 12. No 5G for me. At some point I will call Verizon to find out if I even can get it or I have to change plans. Right now I’m not on any unlimited plan, just 5 GB per month
 
Same here, 4 hours trying with the phone, on line, chat, 3 differ chat agents said phone 12 pro is activated...but get the same verizon recording "unable to complete your call.. contact customer service at*611" Of course they are closed😢 What a night mare
 
Same here, 4 hours trying with the phone, on line, chat, 3 differ chat agents said phone 12 pro is activated...but get the same verizon recording "unable to complete your call.. contact customer service at*611" Of course they are closed😢 What a night mare

Try a power cycle after midnight. If that doesn’t work, let it go overnight. Then restart in the am.

This is what worked for me.

I tried a lot of what was mentioned in this thread.
 
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Try a power cycle after midnight. If that doesn’t work, let it go overnight. Then restart in the am.

This is what worked for me.

I tried a lot of what was mentioned in this thread.

Agree. When I first received my new Sim it did not work for me on my Xs and after talking to tech-support, they told me too wait a couple hours and restart my phone. I waited only about 40 minutes 45 minutes and restarted the phone and everything function properly, so you may have to wait a little while. After I received my 12, I put the new Sim into it from my Xs and it worked perfectly without any issues. Good luck
 
The saga continued today, nothing changed overnight, phone won’t activate no matter what. Tech support back to square one with activation sequence resets etc. No luck. Went to Verizon store, they said they have lots of activation issues and to call tech support about initiating a “ticket” and escalating. Called tech support for the 6th time, said they know nothing about isssues, I insisted to talk to next level support since I had 5 previous contacts with tech support without success... Level 2 tech support magically fixed the activation issue in like 5 minutes ... they wouldn’t elaborate what they did ... go figure🤪
 
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The saga continued today, nothing changed overnight, phone won’t activate no matter what. Tech support back to square one with activation sequence resets etc. No luck. Went to Verizon store, they said they have lots of activation issues and to call tech support about initiating a “ticket” and escalating. Called tech support for the 6th time, said they know nothing about isssues, I insisted to talk to next level support since I had 5 previous contacts with tech support without success... Level 2 tech support magically fixed the activation issue in like 5 minutes ... they wouldn’t elaborate what they did ... go figure🤪
What they don't tell you is that after several attempts at activation, it will lock you out on their servers. All the level 2 tech did was remove your phone from being locked out and activated the phone for you.
 
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