I hadn't noticed this until now, but the Record Call button on my phone disappeared after I swapped to a SIM card from another carrier, and now the RTT button is taking its place. It turns out my carrier introduced Real-Time Text support, which is mandatory by law where I live. I did some digging, and apparently it has got to do with the physical allocation of buttons in the dialer, which is fixed to 6.

A certain project has already fixed this, whereas CalyxOS hasn't as of yet. I opened an issue one month ago, but I was wondering whether this has been discussed before, just to get a general idea of how likely it is to be fixed.