My carrier charges me for roaming calls and SMS but only if I use them while roaming. When abroad I stick to iMessage/FaceTime Audio and I pay nothing for roaming charges.

Except that Airalo doesn’t disable your main line since it occupies a separate eSIM slot, unless you have a 2nd line in there, in which case you’d need to disable it for Airalo to work.

You don't disable your main line, it stays active but is used just for voice/SMS and Airalo line is used for data exclusively, unless you've set the phone to switch cellular data networks if you get a phone call on one of them, which you should turn off when going abroad anyway.

There are no additional charges for the main line if it stays active for voice/SMS, at least not where I live.

You don't change your phone number with Airalo, instead, you get another phone line that's just for data (you don't even get a phone number at all with Airalo eSIM) and you get to keep your main phone number for iMessage/calls/2FA SMS.

Works flawlessly for me every time no matter where I go, and I've been to over 20 countries with Airalo eSIM so far, zero trouble. Highly recommend.