This thread may be of interest VOIP App on e/OS
A search reveals some successes https://community.e.foundation/search?expanded=true&q=SIP%20VoIP%20order%3Alatest
You have framed your title in the negative; is that what you require, a system where you can remove the SIM card ?
In my experience some carriers care to support WiFi calling (example https://mobile.asda.com/help/network-coverage/wifi-calling). Just a thought … is SIM the subject of your thread or SIP / VoIP ?