Cannot be, unless you're saying they have VoLTE.

Maxis always try to promote their 4G network. They also mention 4G a lot on the Hotlink FAST SIM pack. It doesn't mean it's ALWAYS on 4G. You can't make voice calls on 4G, unless VoLTE is available.

Don't think it's open to Malaysians.

Not legally, only through a loophole.

The system is broken. Certainly you can't buy this under your own name if you're a Malaysian.

Digi also has VoWifi for certain phones.

For me, U Mobile is so lousy in my home area it doesn't matter how cheap its roaming rates are.

There is no "stacking" or adding-up of validity days. The very last topup overrides the validity by previous topups unless the validity extension is shorter than the existing validity period.

If your validity was 5 days and you top up RM30, your validity is now 30 days from today. If you top up another RM30 tomorrow, your validity will then be 30 days from tomorrow.

If your validity was 40 days and then you top up RM 30, your validity will still be 40 days because 30 is less than 40.