Just a reminder that VOIP calling only uses about 1Mb of free or paid data per minute.

Dual Sim, Dual Standby phones can make calls just for just pennies per minute of data if you have a reasonably priced (<$2-$3Gb) data plan. I have T-Mobile for free roaming data and a $10 a month US Mobile 2Gb plan on their Warp/Verizon service. It gets free international calls from the US and calls made while roaming are $0 billed as originating in the US while using VOIP-IMS. This system gives me free roaming calling to international numbers while overseas. I have tested this a moderate amount in Europe, Asia, and Central & South America with consistent, stable results.

When I am in the US, the USM Verizon service is available for the rare loss of T-Mobile service, or for calling numbers I'd rather not have caller ID register my daily, main phone number.