Tagging in here to give you the info you asked for.
In CoSoCalls, the mod has an option in the three dot menu to record the call.
Both @tiptoeing and I noticed that an error is displayed when one attempts to record.
If I'm not mistaken, TT uses either Safari or Chrome on iOS, while I tried in Edge on both Android and Windows.
Screenshot of the error attached, taken in Windows Edge, but the error is the same across devices and browsers.