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This is not related to LTE, just to roaming itself. In fact, even the manual of the first GSM phone I ever bought said as much (to store your numbers with the i

This is not related to LTE, just to roaming itself. In fact, even the manual of the first GSM phone I ever bought said as much (to store your numbers with the international prefix on the address book -- otherwise, they could fail to be matched while roaming).

mdb31 5y ago
Well, it is related to LTE, in the sense that VoLTE calls are treated as 'data' (and thus backhauled to your 'home' provider, as per your (e)SIM), whereas 'voice' calls are handled by whichever provider you happen to be connected to. But the advice to always dial calls in 'international' format is helpful.
- AshamedCaptain 5y ago
  In fact the author is describing the opposite situation, where his "LTE calls" require the international prefix while the "Wi-Fi" calls do not require it (not sure if VoWifi or plain VoIP, it's not clear from the description, and I don't know of any phone provider which allows true VoWifi while roaming). Note most modern dialing programs (and likely all of the VoLTE-capable ones) will silently add some prefix to your calls anyway, so it's really hard to know what's going on behind the scenes. But you usually can't dial your provider's special phone numbers "as if your calls where backhauled to their network through VoIP" when you are roaming, even with VoLTE. To e.g. check voicemail you will still need to dial your provider's roaming-specific number, which will come with an international prefix.
nathancahill 5y ago
The fact that iOS (not sure about Android) doesn't automatically add the local international prefix when you store a new contact is surprising. Seems like an easy quality of life win.
- kevincox 5y ago
  Android also doesn't automatically store numbers in international format (at least for the default and Google contacts apps). Maybe the reason is either: 1. The phone doesn't always know the international prefix. 2. This raises the risk of accidental long-distance calls and may piss of users.

mdb31 5y ago

Well, it is related to LTE, in the sense that VoLTE calls are treated as 'data' (and thus backhauled to your 'home' provider, as per your (e)SIM), whereas 'voice' calls are handled by whichever provider you happen to be connected to. But the advice to always dial calls in 'international' format is helpful.

AshamedCaptain 5y ago
In fact the author is describing the opposite situation, where his "LTE calls" require the international prefix while the "Wi-Fi" calls do not require it (not sure if VoWifi or plain VoIP, it's not clear from the description, and I don't know of any phone provider which allows true VoWifi while roaming). Note most modern dialing programs (and likely all of the VoLTE-capable ones) will silently add some prefix to your calls anyway, so it's really hard to know what's going on behind the scenes. But you usually can't dial your provider's special phone numbers "as if your calls where backhauled to their network through VoIP" when you are roaming, even with VoLTE. To e.g. check voicemail you will still need to dial your provider's roaming-specific number, which will come with an international prefix.

nathancahill 5y ago

The fact that iOS (not sure about Android) doesn't automatically add the local international prefix when you store a new contact is surprising. Seems like an easy quality of life win.

kevincox 5y ago
Android also doesn't automatically store numbers in international format (at least for the default and Google contacts apps). Maybe the reason is either: 1. The phone doesn't always know the international prefix. 2. This raises the risk of accidental long-distance calls and may piss of users.