iPhone Xs Roaming Issues

[bantam_w]

I've an iPhone Xs running iOS 13.3

In the UK, the device works as expected, no issues on Wifi or 4G.

Also, roaming in Europe (Hungary, Netherlands for example) again the device seems to work as expected.

However it does not roam properly when in the USA. I have O2 Travel Inclusive Zone (and also seemingly O2 Travel at the same time according to my Bolt-Ons) and although it works, it's very sporadic. I've been travelling quite a bit to the USA over the last few months, and whilst my work UK Vodafone android device seems to spring into life pretty much instantly when I arrive in the US, my O2 iphone takes quite a while to find a cellular network. Then when it does, even if it's got full strength 4G, the actual data roaming doesn't seem to work. Open any app and I can't access the internet. Some apps work but very very badly. iMessage, for example, ALWAYS has a brain fart and can't send any messages once I'm roamed in the US.

Switching it into Airplane mode and back off, after a few attempts it eventually springs into life for a short while and I get bombarded with notifications, before it giving up the ghost from a data perspective once it roams cell sites again. I've tried forcing it to T-Mobile, AT&T and others, turning roaming data on and off, resetting the network settings, changing the APN from idata to mobile. Nothing seems to work. It's just super sporadic. After a day or so in the US it settles down and seems to work, albeit VERY slowly. I try to hunt out wifi wherever I am as the roaming is just horrendous.

(And as an ex O2 employee, I know how roaming works and how little they pay for the interconnect, so I don't expect O2 to give me free US roaming and then throttle it to 500kbits/s in 2020.)

Is this usual? Like I said - roaming works fine in the EU but is chronic in the US. Is this just apps overwhelming the frankly last millennium bandwidth allocation or is there something slightly more nefarious at play?

[MI5]

@bantam_w 

O2 throttle their data speed to 0.5mbps in all countries outside of the EU once you've used the first 50mb per day.

[bantam_w]

Yes, I'm aware of that. (As I said, I'm also aware of how roaming works as I used to work for o2 (not retail - in the back office))

But that shouldn't knock out iMessage entirely, for example. iMessage will only work when on Wifi now (just tested tethering my iphone via Wifi to my roaming works Vodafone handset, and iMessage started to work fine) - whilst I can browse websites in Safari and other apps work (albeit slowly), iMessage just seems to stop working fully. Also, my wife can't call my mobile when it's roamed - the calls seem to just go to a black hole when you call the UK number. And SMS doesn't work either. So there's definitely a fundamental issue with this device when roaming in the US. 

[bantam_w]

Ok. A bit more troubleshooting - looks like it's the exact same issue some users on the gold coast in Australia are seeing.

I can surf web pages via Safari no problem. I can use email via Gmail app. But any communications protocol apps such as iMessage, Facebook Messenger and Whatsapp have stopped working entirely.

As soon as I get onto Wifi they spring to life, but on roaming they stop working entirely for long periods. Then randomly they'll work for a short while when you roam onto a new cell site then stop.

It's also blocking the notification protocol - so the iphone uses server-side apps to drive notifications and there's a channel back to the device that allows the notifications to pop up - that is also being blocked.

This is looking more and more like O2 using a layer 5/6 firewall to block content for specific protocol types for some bizarre reason. Or a misconfiguration in their roaming layer.