For me dual SIM is a hack to beat the overcharging telcos here. My data SIM is the free 1GB mobile broadband SIM that came with my internet. Actually this can be used for calls at slightly higher cost than prepaid, but then then caller ID is charged at $5 a month. So I use a prepaid SIM for calls which has free caller ID. Both my data and calls usage on mobile is very low so this dual SIM setup works for me at very low running costs.
Sent from my Redmi Note 4 using Tapatalk