Dual-SIM phone slots 1 and 2

Basic Question: In Dual-SIM phone, what are the key features when you put a 4G-SIM in slot 1 and slot 2. Will it affect data speed?

Most of dual SIM phones (apart from few latest) don’t support LTE for both SIMs instead SIM 1 can have LTE and SIM2 can have 3G or lower TECH.

Does not seem right. Dual-SIM phones usually operates 1 at a time, isn’t it?

Yes, because other SIM has to read pages, thus a little impact.

Add to that VoLTE support not all handsets are Dual VoLTE which is why SIM 1 is preferred.

@RMatolia, could you elaborate on the reading page impact?
Sorry couldn’t get your point?

Now a days, most premium phones are dual sim dual volte.

And when data is working on one sim, other sim in idle condition will ask for pockets between ongoing data to read paging.
Example, first sim is Airtel, second Jio, data is working on Airtel, in between during drx on for paging on Jio, it will take RF resources to read paging.

True. Got you now.