I would have preferred to post this in the offtopic forum since it is regarding services around Asterix rather than a technical subject involving Asterix directly.
I have noticed innovators in international simcard operators.
Some are offering 2 numbers in one simcard, even with roaming and another is offering some kind of VoIP intergration.
I don’t suppose you have any ideas on the technicalities behind such new setups, or what to search for for more info?
AFAIK the dual number ability is part of the GSM standard but the VoIP linking sounds intriguing.