Will Quick Start transfer all visual voicemails to a new phone from a new provider?

And the answer is...

QuickStart successfully moved all the voicemails from an iPhone 11 associated with an AT&T account to an iPhone 14 on TMobile along with all other data. Phone to phone transfer. Voicemails appeared once the voicemail passcode had been entered. Had made an iTunes backup of the 11 but it was unneeded.

Thank you Mr Finch.

Your understanding seems to differ from TMobile's: "T-Mobile Visual Voicemail app (VVM) for Android allows you to listen to and view messages in any order, on your phone... This app is only for Android devices, Apple iOS devices use a built-in voicemail app. For help with the iPhone app, see Check your voicemail on iPhone - Apple Support."

Also, my brother has been a TMobile subscriber for more than a decade. He's moved up through several iPhone models, and despite the fact that TMobile deletes VMs on their servers after 30 days, he has TMobile voicemails going back to 2016 and accessible today through Phone | Voicemail. All the old VMs moved from one iPhone to the next via Apple's transfers like QuickStart. This seems to prove that an iPhone syncs VMs with the provider as the VMs become available, but thereafter those VMs are accessed off the phone.

What's unknown here is whether a new iPhone - one using the same phone number as an old iPhone but coming from a different provider - will successfully restore those saved VMs from the old iPhone's backup.

Thank you @lexOS1. In the searches I've done, this is pretty much the same info I've found - a smart suggestion, but no actual answer to the question.

What's frustrating is that there does not seem to be any definitive answer about something that happens very frequently: When you changed providers, had them port your number, and got a new phone, did your your new phone have all the VMs you had on the old phone? <crickets>

This seems like something Apple would know. Maybe for some reason, though, it's a provider-specific situation. But in that case, it seem certain that this is something the providers see daily. How is it that answer doesn't seem to exist?

Thanks for the suggestion to keep the backup.

If I had a handful of VMs using the share sheet would be workable but I have many, many more. Having them each in emails.... ugh. Perhaps sending them into Voice Memo might make sense if it weren't for how many need to be touched.

I see there are a few programs that can suck VMs out of a connected phone or its backup, and can automate saving them in a sensible way, but that's $40 I'd rather not spend if it turns out that the VMs do transfer using QuickStart.