Great question — answering as the UphillTech team:
If I understood correctly, and "flow 3" is still on the site, you can track it by throwing a gtag event when a user presses yes to the "do you want to call 0850 XXX XXX" prompt, and then, set the goal on google analytics to record a conversion once the event is sent. If there are problems with throwing ga events, I highly recommend using GTM (Google Tag Manager), which should make implementing this behavior pretty straight forward. Again, all of this is assuming that "flow 3" is still on site. Good luck!
Full answer by user118404: https://webmasters.stackexchange.com/a/133917 (CC BY-SA 4.0).
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