TPG有个TPG 4G Voice app。最便宜的套餐10块钱一个月（senior plan是5块钱）。

漫游的时候接电话不要钱，打电话算新加坡的分钟数。

原文（重点加粗了）：

If you are using a TPG VoLTE supported mobile device while roaming on a VoLTE supported roaming network, you will be able to make and receive calls while roaming. Alternatively, you can download TPG 4G Voice app to make and receive calls. When roaming, all incoming and outgoing calls from and to Singapore mobile numbers are free. Calls to Singapore fixed line numbers will be deducted from your existing plan’s local free minutes entitlement. Calls to other countries including the roaming country will be either deducted from your free 300 IDD minute entitlement for 80GB SIM Only Plan or from your cash wallet for other plans.