Thank you for all the replies.
After reading up on the way most dual sim phones work, I now have a follow up question - either I am missing something obvious, or their utility is becoming limited to fewer and fewer countries. Hopefully someone more knowledgeable would be able to clarify.
According to a number of sites (
https://www.ozbargain.com.au/node/236535 as an example) even Dual Sim Active phones actually only support LTE on one sim at a time . The other sim is relegated to a 2G connection, even on the newest phones.
So what happens in countries which are turning off their 2G networks (such as Australia in December (
https://crowdsupport.telstra.com.au/...ng/ba-p/440992 )), Singapore and many others ?
Not to mention that even in many developing nations, the network build out has essentially leap-frogged 2G - 2G networks exist only in major cities while LTE is already in the most random of places.
Does the 2nd slot become completely useless in those cases?
Are there dual sim phones which actually keep both SIM cards active and connected to LTE or at least 3G networks? So far I've only been able to find one phone from Xiaomi with such a feature, but that one is mostly limited to Chinese LTE bands.