VoWiFi
You don&#x27;t need eUICC or anything of the sort to do roaming, which is just what he&#x27;s describing. Even the behavior with the international prefix on numbers.<p>Also, the simultaneous data + voice story is kinda more complicated. You couldn&#x27;t do simultaneous voice+data on 2G phones. You could do it on UMTS&#x2F;HSDPA for sure (it was one of the marketing points...). Then when LTE came, for a time phones could not do phone calls over LTE (VoLTE) (something which I was told was just a &quot;missing software thing&quot;) so they had to drop down to some 3G standard during any phone call. If your 3G standard didn&#x27;t have support for simultaneous voice+data, like it used to be on CDMA networks, then you just didn&#x27;t have data (see CDMA iPhone 5). But it was just fine on GSM ones.