Visual Voicemail not working on iPhone iOS16

I'm using iOS 16.5, and I've seen other posts on Apple forums that point to this same issue on iOS 16+. Whenever I get a call that results in a voicemail I get a text with a string of characters like "//VZWVVM:SYNC..." that a bit of research shows me are intended to be cues to the iPhone Visual Voicemail app. The voicemails aren't showing up there though, at least not reliably. I can usually just call into my vm box and get the vm's but they're not visible anywhere in the phone app. I've tried reseting my cellular settings, clearing out all my old voicemails, checking for call forwarding, resetting my network settings, etc. Apple pointed me to Verizon as the cause. Has anyone had this issue? Verizon support won't even respond to any messages on this.

Accepted answers

mrNoVoicemail

UPDATE: To document this for the group, the issue was tied to the fact that I briefly swapped from my iPhone to an Android phone and then back to my iPhone. The messaging being sent to my phone via the VVM commands I outlined in my original post were meant for an Android phone. For some reason the swap back to iOS never happened on the Verizon side.

The Verizon support team was able to recognize this pretty quickly and fix it almost immediately once the right people were looking at it. So it's an easy fix, but not self serviceable.

What I'd really like to see on the Verzion side to keep things like this from happening again is maybe a response header check that looks for a mismatch in the phone's user agent. This seems like a preventable issue, but either way the team was very quick in addressing it after I brought it to their attention.

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Verizon_Support

Hello,

We want to do all we can to help make sure you are able to access your voicemails as this is a crucial feature. We are sending a Private Note to assist you.

-Colin

mrNoVoicemail

Since getting a reply to this message I've received a series of texts with the string "//VZWVVM:STATUS:st=R;rc=0;srv=ws1lv.imsvm.com;ipt=143;u=[email address removed per the Verizon Terms of Service];pw=WxecHxR6MYIyZyv;lang=1,2,3,4,5,6,7,8;g_len=60;vs_len=10;pw_len=4-7;dev_t=5;vmg_url=https://vmg.vzw.com/VMGIMS/VMServices"

That link leads to me a "Whitelabel Error Page" with a 405 status

mrNoVoicemail

The Verizon support team was able to recognize this pretty quickly and fix it almost immediately once the right people were looking at it. So it's an easy fix, but not self serviceable.