One of the reasons I bought the One Plus Two was because it had dual sim card slots. There are a lot of Chinese phones that have dual SIM card slots, but the OPT is one of the first ones with Western world support (the other being ZenPhone 2). From past research I knew that usually dual SIMs meant that the second sim would be GSM only, so before deciding on the OPT, I did research to verify that both slots could indeed support 4G.
While my OPT arrived last week, my Micro B to USB type-C adapter didn’t arrive until this week, and I went out on the weekend to do SIM swaps from micro to nano (WIND waived the fee and Bell charged me $10). However, when I tried both SIMs, I could only connect to one network at once! I tried a bunch of things and thought that I had a software caching issue (I had used the AWS SIM first and then switched its slot, maybe the first slot was still looking for a network on AWS).
Anyways, it turns out that while it didn’t matter which slot I put the SIM cards (i.e., both supported 4G networks), only one could work on 4G at once. The other had to work on GSM. I guess this kind of made sense – OnePlus didn’t bother embedding 2 4G radios in the phone. But it basically broke my use case because neither WIND nor Bell has a GSM network so I couldn’t use both SIM cards at once. Even if one of my providers had a GSM network, I don’t think it would satisfy my use case, because I wanted 3G data fallback and 3G/LTE data can only work on one SIM card at one time.
In the end, I decided that my strategy would be to carry both SIMs but only use one at once. At least this way if I hit one of the WIND deadspots, I can switch to Bell. The switching process is kind of a pain though, hopefully I can write a quick Android app to make the process one-click.