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Unfortunately not @Phil2die4 you won't be able to use WiFi calling on your LG phone, it not one of the supported devices, there is also the added problem of the phone previously used with Verizon, this would mean there may be remaining Verizon software preinstalled on the phone. See below.
edited to add: @Phil2die4 The V40 was released October 2016 exclusively for the US market, there is no way you will be able to add WiFi calling with Vodafone in the UK.
If you need WiFi calling, you will need a supported device and be on an eligible tariff here: Who can get WiFi calling?
Have you imported the phone from the States to the UK to then use on the Vodafone UK network on an eligible Vodafone Contract ?
I've seen before where a person has been able to use a phone that's not been added to the Vodafone UK Calling Over Wi-Fi eligible phone's list.
Check if the option is in your myvodafone.
It can't harm to ask a Vodafone UK Customer service Agent.
Calling Over WiFi Set up.
Ask the agent to force the phone via sending an OTA configuration update that should provision your phone for Calling Over WiFi.
"Register for Vodafone Wi-Fi Calling
Text the word CALLING to 97888
This is a free text which will add the service to your account
You should receive the following confirmation text:
Thanks. We’ll add Wi-Fi Calling to your account in the next 24 hours and will let you know when you’re all set up.
If you’d like to discuss this with us, or if you have any other issues, you can find more info here or contact us
Once you receive the confirmation text, switch on Wi-Fi Calling in your settings
Go to Settings, scroll down and choose the Application icon
Choose Phone and scroll down until you see Wi-Fi Calling – select the box beside this option
A pop-up will appear asking you to confirm if you want to enable Wi-Fi Calling – tap OK"
I've also known people to change the current firmware on the phone to Vodafone Uk's to get certain features working. If you consider this then do some good homework via a Google Search to see if this is viable and on how and be aware of all the pro's and con's of performing this.
I wish you all the best with this.
Current Phone > Samsung Note 20 Ultra 5G - SM9860 Snapdragon.
Samsung One Ui 2.5 / Android 10.
I agree that it's unlikely it's work in your case, but I have heard of people getting wifi calling on apparently unsupported devices by asking Customer Services to force send the correct APN to the device, so that might be worth a go.
Speaking of which, I really must do that myself...
Vodafone doesn't support WiFi calling on LG phones. I have used LG phones for years and they always supported Samsung and iPhones no matter how top of the line or premium your LG is. This has been going on for years now.